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一点意见：铁在氧气中燃烧，生成致密的四氧化三铁，覆盖在铁的部分表面。铁继续燃烧，生成强热，使铁与四氧化三铁之间空气膨胀，将四氧化三铁崩开，因此铁燃烧的现象是火星四射。镁在氧气中燃烧，生成疏松或粉末状氧化镁，在燃烧时只会产生烟或直接掉在瓶底，不会火星四溅。铁的沸点是2750摄氏度，在氧气中燃烧时不易升华，形成等离子态（火焰）。 镁的沸电是1090摄氏度，在氧气中易升华，而形成等离子态（火焰）。另外，铁燃烧生成四氧化三铁，在一定程度上阻碍了铁的升华和与氧气的接触；蹦出的四氧化三铁带走了大量热量，也使铁无法达到较高温度而升华。因而铁燃烧无火焰。而镁却正相反，故有火焰。
化学是一门自然科学，是中学阶段的一门必修课，它是古往今来无数中外化学家的化学科学研究和实践的成就，它编入了一些化学基本概念、基础理论、元素化合物知识、化学反应的基本类型、无机物的分类及相互间的关系等知识；它充满了唯物辩证法原理和内容，它介绍了许多科学家的优秀品质和他们对事业实事求是的科学态度、严谨的学风。化学对工农业生产、国防和科学技术现代化具有重要的作用，人们的衣、食、注行样样离不开化学。化学是一门实验科学，通过化学课的学习，要掌握一些化学实验的基本技能，学会动手做实验的能力，为今后搞科学实验打下基础。因此，通过初中化学课的学习，初三学生不仅能学到初中阶段的系统的化学基础知识，受到辩证唯物主义思想、中外化学家的爱国主义思想、行为和对科学的不断进娶不断探索、不断创新的科学态度及严谨学风的教育，而且还能提高自己的观察能力、思维能力、实验能力和自学能力，为今后学习高中化学及其他科学技术打下良好的基础。作业请独立完成,xiexie 答案补充 要向我一样总分格式，有关键词，结论最重要结论是整篇文章的最后总结。结论不是科技论文的必要组成部分。主要是回答“研究出什么”(What)。它应该以正文中的试验或考察中得到的现象、数据和阐述分析作为依据，由此完整、准确、简洁地指出:一是由研究对象进行考察或实验得到的结果所揭示的原理及其普遍性；二是研究中有无发现例外或本论文尚难以解释和解决的问题；三是与先前已经发表过的(包括他人或著者自己)研究工作的异同；四是本论文在理论上与实用上的意义与价值；五是对进一步深人研究本课题的建议。3.8 参考文献它是反映文稿的科学依据和著者尊重他人研究成果而向读者提供文中引用有关资料的出处，或为了节约篇幅和叙述方便，提供在论文中提及而没有展开的有关内容的详尽文本。被列入的论文参考文献应该只限于那些著者亲自阅读过和论文中引用过，而且正式发表的出版物，或其他有关档案资料，包括专利等文献。
化学课程是从化学科学中选择部分内容,从学校课程体系出发,安排它的顺序、课时及期限。下文是我为大家搜集整理的关于初三化学小论文的内容，欢迎大家阅读参考! 初三化学小论文篇1 溶液溶解度的探究 上周，我们已经学完第九单元《溶液》课程的全部内容，在回顾单元知识的过程中，我着重回忆对溶解的加深理解，记得课后还曾经向刘老师求教空气和合金也是溶液，也有溶解度的概念，刘老师还在课上告诉我们一些溶液的形成和物质溶解时伴随着吸热和放热现象等等。为了深入理解溶液溶解度的概念，我和同学利用假日期间，通过做化学小实验来探究物质能不能无限地溶解在一定量的某种溶剂中，即溶解度的知识点。 我们在1月2日中午(室外温度13度左右)的情况下，做有关溶解度实验。 首先将超市购买的精制250克食用盐均匀分成5份，每份50克; 其次，将超市购买的550mL的农夫矿泉水缓缓倒入奶锅内，防止水溅出; 第三步，略微加热装有矿泉水的奶锅，并用筷子搅拌均匀后，用甩至0度的体温计测量奶锅内的矿泉水温度，为19度。随后加入1份50克的食盐，搅拌后全部融化。 第四步，再加50克的食盐，搅拌后仍能全部融化。 第五步，再加第3份50克的食盐，搅拌后观察，发现锅底有少量食盐未能溶解。 这时，我们查阅相关资料，得知“在20°C时,食盐的溶解度为36g”，我们计算550毫升的矿泉水约为550克，在20°C时可最多溶解146克的食盐。 因而，我们分析，此时奶锅里的溶液应为饱和溶液。 第六步，我们将奶锅里的溶液加热，一会儿，发现，沉淀锅底生物少量食盐不见了，因此，判定，此时溶液可能是不饱和溶液，说明溶解度与温度相关，随着温度升高，溶解度变大。 第七步，将热的奶锅放在室外(10度左右)1小时候后，观察，奶锅里又有少量的食盐沉淀物出现，说明溶解度与温度相关，随着温度降低，溶解度变小。 通过这次实验，我们进一步理解了以下几个知识点： 1、饱和溶液：在一定温度下，在一定量的溶剂里，不能再溶解某种溶质的溶液。 2、不饱和溶液：在一定温度下，在一定量的溶剂里，能继续溶解某种溶质的溶液。 3、将溶液加热(升温)可以使溶液由饱和状态变成不饱和状态，将溶液冷却(降温)可以使溶液由不饱和状态变成饱和状态。 初三化学小论文篇2 归纳一二三轻松学习碳 碳和碳的化合物可以说是化学世界里最庞大的家族，它们有超过二千万的成员。划玻璃用的金刚石，写字用的铅笔芯，我国古代的一些书法家、画家书写或绘制的字画用墨等等。近年来，科学家们发现，除了金刚石、石墨外，还有一些新的以单质形式存在的碳。其中，发现较早并已经在研究中取得重要进展的是C60分子等。那么同学们如何学好关于碳单质的知识呢?实际上我们只要善于总结，就能学好碳知识。 抓住一条主线 物质的结构决定物质的性质，物质的性质决定物质的用途。在学习碳的单质时要抓住“结构→性质→用途”这样一条主线。 对于几种常见的碳单质的结构、性质、用途，我们同学们要注意总结，并善于发现其中的内在规律，这对于掌握好碳的知识是非常有帮助的。 记住两种单质 金刚石和石墨是最常见的两种碳的单质，这就要求同学们记住这两种物质的性质和用途。金刚石和石墨虽然都是由碳元素组成的单质，但由于碳原子的排列方式不同，决定了它们的物理性质有很大的差异。 (1)金刚石中碳原子连接成牢固的立体网状结构，决定了金刚石具有坚硬的性质，由此决定了其可制作钻头、玻璃刀的用途。 (2)石墨中每个碳原子与同一个平面上周围的三个碳原子连成片，许多这样的片重叠起来构成石墨。由于每个碳原子都剩余一个电子成为自由电子，所以石墨能够导电，因此可制作电极;片与片之间可滑动，所以石墨质软，可制作铅笔芯、润滑剂;碳原子之间连接很牢固，所以它的熔点、沸点都很高，可用于制作航天飞机的绝热片。 另外，对于木炭和C60也要熟悉。木炭具有疏松多孔的结构，决定了它具有很强的吸附性，可作吸附剂。活性炭的吸附性比木炭还要强。可用于防毒面具里的滤毒罐、制糖工业上的脱色剂等。C60分子是由60个碳原子构成的分子，这种结构很稳定，决定了它具有许多特殊性能。 掌握三个性质 由于碳原子最外层有4个电子，在化学反应中，碳原子既不易失电子，也不易得电子，决定了碳是一种化学性质不活泼的非金属元素，而且同学们要注意，虽然金刚石、石墨、C60的物理性质不同，但化学性质却是一样的，因为构成它们的粒子是同一种粒子—碳原子。 (1)常温下的稳定性：在常温下，单质碳化学性质很稳定，不易与其他物质发生化学反应。因此，可用碳素墨水书写档案材料，这样可以长时间保存而不褪色。 (2)可燃性：在点燃的条件下，碳能与氧气反应，放出热量，决定了碳可用作燃料。 ①氧气充足时，碳充分燃烧，生成二氧化碳。 C+O2CO2 ②氧气不充足时，碳燃烧不充分，生成一氧化碳。2C+O22CO (3)还原性：在高温条件下，碳能跟某些金属氧化物发生反应，把金属氧化物还原成金属单质。碳表现出还原性，决定了碳可用于冶金工业。例如： C+2CuO2Cu+CO2↑ 3C+2Fe2O34Fe+3CO2↑ 猜你喜欢： 1. 化学毕业论文精选范文 2. 材料化学论文范文 3. 化工专业毕业论文范文 4. 化学毕业论文范文参考 5. 化学毕业论文范例
某研究小组在学习氧气的化学性质时发现：铁丝在氧气中燃烧没有火焰，而蜡烛在氧气中燃烧却有明亮的火焰．该小组同学进行了如下探究．①探究一：蜡烛燃烧产生火焰的原因是什么？点燃蜡烛，将金属导管一端伸入内焰，导出其中物质，在另一端管口点燃，也有火焰产生（如右图所示）．由此可知：蜡烛燃烧产生的火焰是由气态气态（填“固态”或“气态”）物质燃烧形成的．②探究二：物质燃烧产生火焰的根本原因是什么？【查阅资料】物质 熔点╱℃ 沸点╱℃ 燃烧时温度╱℃石蜡 50∽70 300∽550 约600 铁 1535 2750 约1800 钠 97.8 883 约1400 由上表可知：物质燃烧能否产生火焰与其沸点沸点（填“熔点”或“沸点”）和燃烧时温度有关．通过上表中石蜡、铁的数据对比，你认为物质燃烧时，什么情况下能产生火焰沸点低于燃烧温度时能产生火焰沸点低于燃烧温度时能产生火焰．由此推测：钠在燃烧时，有有（填“有”或“没有”）火焰产生．③根据硫在空气或氧气中燃烧的实验事实，请你推测硫沸点＜＜硫燃烧时的温度（填“＞”或“＜”或“=”）考点：蜡烛燃烧实验．专题：科学探究．分析：①根据题干提供的信息结合所选知识进行解答；②由表格数据进一步探究物质燃烧能否产生火焰与其熔点、沸点和燃烧时温度的关系，并用实例说明；③根据硫在空气或氧气中燃烧有火焰的实验事实，进行分析解答．解答：解：①由实验探究蜡烛燃烧产生的火焰的原因：点燃蜡烛，将金属导管一端伸入内焰，导出其中物质，在另一端管口点燃，也有火焰产生（如题干图所示）．由此可知：蜡烛燃烧产生的火焰是由气态物质燃烧形成的；②由表格数据进一步探究物质燃烧能否产生火焰与其熔点、沸点和燃烧时温度的关系：分析蜡烛的熔点、沸点和燃烧时温度，发现其燃烧的温度比沸点高，燃烧产生了火焰；分析铁丝的熔点、沸点和燃烧时温度，发现其燃烧的温度比沸点低，燃烧不产生火焰；分析钠的熔点、沸点和燃烧时温度，发现其燃烧的温度比沸点高，故推断其燃烧能产生火焰；③根据硫在空气或氧气中燃烧有火焰的实验事实，推测硫沸点＜硫燃烧时的温度；1、气态物质燃烧才会有火焰，所以物质燃烧有没有火焰关键看这个物质在燃烧前有没有汽化，如果可燃物先变成气态，那么可以观察到火焰，否则只会有发红、火星、强光等现象。由于铁的沸点非常高，所以铁丝燃烧时并没有变成气态，所以观察不到火焰，只有火星四射（高温熔融物溅出），镁带也是如此所以只有耀眼白光，铁、铜在氯气中燃烧也这样的。、2、铁中含碳量不同， 则实验现象不同 上面图中甲瓶与丙瓶显示的都是铁丝在氧气中燃烧的现象，为什么甲瓶中的火星明显没有丙瓶中的多呢？其实就是它们含碳量不同。较纯的铁丝（工业级）在氧气中燃烧火星较少，弯成螺旋状有时不能燃烧，或燃烧不能持久，采用较多量铁丝疏松缠绕在一起燃烧现象与上图中甲瓶类似；低碳钢铁丝，弯成螺旋状产生火星的数量与甲瓶类似，反应有时不能持久；中高碳钢弯成螺旋状很容易剧烈燃烧，火星四射，本人常采用圆珠笔内的弹簧做该实验，效果很好，从来没有失败过，现象如上图中丙瓶所示。很多老师用窗纱上的细钢丝做铁在氧气中燃烧实验失败了，其主要原因应该是窗纱上的纺织钢丝是低碳钢，以前资料一般解释的有氧化膜、氧气不纯、没有达到着火点等原因虽然存在，主要原因还是含碳量太低。
One Sunday my mother (Mother) had (made) me take my little young brother to the a trip to the country. She bade me take good care of him.While we were walking along the road, the sun was shining brightly the breeze was blowing gently. We saw the beautiful flowers *** ile ( *** iling) at us heard the birds sing (singing) their sweet songs on the trees. The scenery was indeed very pretty (beautiful).When we felt tired, we returned home. We saw Mother (our mother) wait (waiting) for us at the door.有一个星期日，我母亲叫我带小弟弟去乡村游历。
她吩咐我要好好照料他。当沿着道路行走的时候，太阳灿烂地照耀着，微风轻轻地吹着。
看见美丽的花儿对微笑着，并听见鸟儿在树上唱着悦耳的歌曲，风景实十分美丽。当感觉到疲倦的时候，就回家了。
看见母样正在门口等候。How to study during summer holiday Summer holiday is ing.Students can have a rest.But we still need to study.So how to study in vacation is a problem. First,we should make a plan before we do the homework.And then we should study with it.It will promise us that we can plete（完成） the work on time.So we won't be so hurry before school begins.Second,we'd better to do the homework carefully,or we can't have good study effect.Third,after we finish doing our homework ,we can have the preparation（预习）for the new term（学期）.It will help us to study easier in the class . This is my opinion.I think these things can make us have a good summer holiday .I think I will enjoy my holiday.And you?My Summer PlanI am glad that summer holiday is approaching.I'll be able to enjoy and relax myselve,which is not easy for me,a pre-graduated student.In order to have a meanningful holiday,I made a plan.First,I would like to do some housework at home.such as cleaning the room,washing the dishes,watering the flowers.Then I am going to do some exercises,including ball games,running.Finally,I want to work at my study.I'll go over my lessons and pratise my English.。
Polar bears are one of most beautiful animals in this world, but their home, the Arctic, is now in danger. Environmental pollution and global warming are seriously threatening their habitat. Arctic summer sea ice could disappear by 2030, according to climate models. Being already lack of food, they have to be near human settlements where they often acquire a taste for garbage, and that brings bears and humans both into perilous proximity. Based on current projections, scientists say that o-thirds of the world's polar bears could be extinct by mid-century, though a significant cut in greenhouse gas emissions could help halt that decline. So measures should be taken to protect the environment on which they are relying. First, governments should legislate to protect oceans as well as the atmosphere. Second, voices should be made to teach the public of the importance of environment protection. Third, enterprises should pay special attention to the effect they have on the environment and work out solutions for the problems. Of course, every individual should try one's best in daily life by saving water/energy, driving less and so on.译文： 北极熊是在这个世界上最美丽的动物之一，但他们的家，北极，目前正处于危险中。
环境污染和全球气候变暖正严重威胁它们的栖息地。根据气候模型，北极夏季海冰到2030年就会消失。
因为它们已经缺乏食物，它们开始侵扰人类32313133353236313431303231363533e59b9ee7ad9431333330363239住区附近，甚至是吃垃圾，这会让熊和人类的距离近的危险。 根据目前的预测，科学家们说，到本世纪中叶世界上北极熊的三分之二就可能已经灭绝，但显著削减温室气体排放量可以帮助制止这种趋势。
因此，应采取措施，保护环境。首先， *** 应立法保护海洋和大气。
其次，教导大众保护环境的重要性。第三，企业要特别注意它们对环境的影响，并制定出问题的解决方案。
当然，每个人都应该在日常生活中尽量保护环境，例如节约水资源/能源，少开车，等等。
As regards the study pressure in universities, students vary in their opinions. Some argue too much pressure is harmful to their academic life, while others regard pressure as a driving force that encourages them to work hard and be top students.As far as I am concerned, too much pressure from study will do harm to my academic life. First and foremost, being overburdened by study, students will be exhausted and bee less creative.Moreover, excessive tensions will do no good to their physical health. Only a sound body could guarantee longterm efficient academic study and research.As the proverb goes, “All work and no play makes Jack a dull boy.”It is suggested that university students balance work and leisure by putting aside enough time for relaxation. Only in this way could higher efficiency in academic study be ensured。
Life is like a mirror, you *** ile to it, it you laugh, you cry it, it will cry for you, anyway, is a happy day, is not a happy day, why not do a little happy? So, with a *** ile in the face Life. In the face of life with a *** ile, it can raise your self-confidence, so that we will be able to do much more effective, we came to this world naked, naked and can not go back, right? Otherwise, it came to the world that has been going on in vain. If Everyone with a *** ile in the face of life, then the world will not be a bad guy, we do not have to sleep all closed down. "In the face of life with a *** ile," these words will acpany me through my life!。
My hometown is in a city which is not very large.There are not any high buildings,and the streets are not very wide.But it is really beautiful with lots of hills and lakes. The climate is very suitable for people to live.In my hometown,you can find many places of entertainments,such as,tea houses,bars and cafe bars and so on.And they are all in the same street.Many people who have visited here say that it is just like a *** all Hongkong.If I can change my hometown,first of all, I'd like to build a entertainment park,just like the Happy Valley.I think that people can relax themselves at the weekends.Meanwhile,people have a place to have the social munication.Certainly enough,it can promote the local economy and beautify the environment.Anyway,that's my dream.I know that I have to work harder to realize my dream. Declarative（陈述句）My elder brother was a very clever boy in his class in the middle schoolInterrogative（疑问句）Do you always help the other people when they are in trouble?Imperative（祈使句）Come back home,or you will catch a cold in such a cold day.Exclamatory（感叹句）How interesting the story is!Simple（简单句）He is a good at handwriting.Compound（并列句）Are you serious or are you kidding at this matter?Complex（复合句）I don't like the cities where it is so noisy and crowded.Compound—Complex（复杂句）Being a student,you should work hard at your lessons which can help you get matured.Long Sentences（长句）Thinking about the problem,he looked at his text-books on the table when he finished his homework which makes him bored and tired as well.Periodic（圆周句）He is a busy man,and the busy man is him.Bakabced（对称句）He is very clever,but,he is very lazy.。
考试作文1: Title: A Strange Dream Time Limit: 30 minutes Word Limit: No less than 120 words 参考范文A Strange Dream It was a sweet spring. How pretty it was! I sat on the green meadow and glanced over my book. The warm winds blew gently. I was very tired and lay down to rest for a little while. Very soon I went into a state of dreaming. A little girl sleeps in a corner of the garden. She cries and cries until her sound is broken. Suddenly a bright figure appears before the child. A beautiful fairy stands in front of her. She had a wand in her hand. “Why do you cry? What's the trouble? Perhaps I can help you”, the fairy says. “My mother is dead. I am lonely, and nobody loves me”, answers the girl. “I am a fairy, my home is in the moon. Do you see the light of the moon? How pleasant it is. Would you like to live with me in the moon?” “Thank you, dear fairy, I want to go with you”. The fairy leads the girl into a wood where there are many dwarfs. They look very busy. Every one of them has to dig the soil. They are trying to find varieties of seeds. They cultivate the fields with their hands. All day long though they are exhausted, yet they are forced to work on. Otherwise they will be whipped to death. I made up my mind to save all of those dwarfs. The sound of the bell suddenly came to my ears. I had to wake up. Oh! This is no other than a dream. I will not let it trouble my mind. (264 words)考试作文2: Title: A Visit to My Uncle (Grandfather，… ) Time Limit: 30 minutes Word Limit: No less than 120 words 参考范文A Visit to My Uncle I spent the winter vacation at my hometown last year. I went to visit my uncle on the following afternoon of my arrival, acpanied by my brother. The weather was bitterly cold. Drifts of snow were frozen up by the strong north wind. We wore fur gowns and walked closely together, but still shivered from time to time. My uncle's house was at the other side of the hill, near the city wall. It is a shorter way to go across the h1ll and down straight to his door. We went by that way to his house. When we got on the top of the hill, his house was already within our sight. Then we quickened our paces, excited with a sort of passion which was very dear to us from years pas? We fot the cold already. My uncle was still the same as I remember him. His laugh, his voice and his gesture, were all as familiar to me as if we had not parted even one day. He was still very healthy. He treated us very kind. He asked to prepare tiff for us in spite of our protest. We said that we could eat only a little, since we had already taken much food, but his warm entreaties made us empty all the dishes. I spent the whole afternoon with our cousins in the country. I was very happy to enjoy the fine scenery in the country, and to breathe some fresh air. When it was growing dark, we started for home. On the way back, we talked about the pleasure of the country people and the pain of the farmers. (275 words)考试作文3: Title: The Person I Admire the Most Time Limit: 30 minutes Word Limit: no less than 120 words Outline: (1) His / Her identity (2) Reasons for my admiration (3) My conclusion 参考范文The Person I Admire the Most Mrs. Fulmer is my English instructor. She es from the U.S.A. Like most of my clas *** ates, I think of her as a repeatable person. She is also very popular among us. Mrs. Fulmer has many of the qualities that students appreciate in an instructor. First, she is cordial and patient. Whenever dealing with new teaching material, she tried hard to get every detail to all students. In addition, she understands our difficulties and does her best to help us get over them. Second, she has an expressive look and an impressive tone. So she always manages to make her lectures interesting and exciting. Finally, Mrs. Fulmer is a very capable anizer. All of us appreciate the schedules of assignments she gives us at the beginning of a term. They allow us to plan our time reasonably and efficiently. Personally, I trust that as a dedicated woman. Mrs. Fulmer is believed to be a successful English instructor. (156 words) 考试作文4: Title: A Person's Birthday Time Limit: 30 minutes Word Limit: No less than 120 words 参考范文Jim's BirthdayYesterday was Jim's birthday. He got a lot of presents from his friends and family. All the gifts were wrapped in colored paper. Some of the packages were large, but others were very *** all. One square package was blue; there was a book in it. Another one was long and narrow; it had an umbrella in it. Jim's sister gave him a big, round package. He thought it was a ball, but it was not. When he removed the yellow paper that coveted it, he saw that it was a globe o。
Whereas other societies look to the past for guidance, we cast our s forward（面向未32313133353236313431303231363533e59b9ee7ad9431333238663036来）It is the belief in a brighter future that gives us optimi *** .Even these days, when not all progress seems positive (nuclear weapons, air pollution, unemployment, etc.), the belief remains that for every problem there is a rational solution.The job of the parents is to give the children every opportunity while they are growing up and then get out of their way.What deference people in authority do mand is based on their actual powers rather than on their age, wisdom, or dignity.In a society that changes as fast as ours, experience simply does not have the value that it does in traditional societies.It has taken a long time to convince the public that free enterprise does not mean that a pany should be free to pollute the air, foul the rivers, and destroy the forests.The assembly line reduced workers to cogs of machinery and made their jobs unutterably boring, but it produced goods fast.Food is prepackaged and shopping is impersonal, but the efficiency of the operation produces lower prices and less shopping time.。
You may feel that college life is boring.We do not know how to deal with the plenty of spare time.But I think the college life will bee wonderful as long as you make it meaningful.In your spare time,you could play basketball,football and so on.Doing sports is very interesting and good for your health.In fact,you can do anything which you are interested in.Do not be nervous.We are friends.Studying in college is a brand new start of our life.You can continue to study hard for the better scords.Libary is a good place for students to study in.If you want to show your talents and skills you can join in all kinds of activities.In a word,college life is wonderful!。
There are four seasons here in Beijing. Spring, summer,autumn and winter.Now it is spring. The weather gets warmer and warmer. But sometimes it has lots of winds. The flowers are everywhere and grass is green. The trees turn green and swallows e back. It's best to fly kites in spring.Summer es after spring. It lasts from June to August. It's the hottest season of the year. People like to go swimming in summer. Students have a summer holiday for about o months.Autumn is a harvist time. Farmers are busy with their crops. The sky is the bluest of the year. We often celebrate Mid-autumn Festival in October.Winter lasts from December to February. It is the coldest time of the year. People like to ski and skate in winter. It sometimes snows then children go out and play with the snow。
I want to go to Australia because it is a beautiful country. It has a rich range of events and festivals to plan my holiday around. Visit for world-class events such as the Grand Prix, Australian Open tennis or the Melbourne Cup.I will also head to high-profile sporting matches such as the Ashes, Bledisloe Cup or Australian Rules Football and immerse myself in the arts and music festivals that enliven the cities each summer. I will indulge in concerts, musicals, ballet, opera and theatre and join exuberant parties like Sydney's NYE celebrations.During summer, we can discover the surf lifesaving and surf carnivals along the coast. In winter, tackle a marathon or endurance event. Or travel to sacred Aboriginal festivals and madcap outback events such as the Camel Cup or Henley-on-Todd.Australia's events and festivals range from local events to world-famous celebrations and happen across all seasons and destinations. Wherever and whenever, I would defintely want to give this country a visit。
The vast majority of television advertisements today consist of brief advertising spots, ranging in length from a few seconds to several minutes (as well as program-length infomercials). Advertisements of this sort have been used to sell every product imaginable over the years, from household products to goods and services, to political campaigns. The effect of television advertisements upon the viewing public has been so successful and so pervasive that it is considered impossible for a politician to wage a successful election campaign, in the United States, without use of television advertising
Microeconomics is a branch of economics that studies how individuals, households and firms make decisions to allocate limited resources,[1] typically in markets where goods or services are being bought and sold. Microeconomics examines how these decisions and behaviours affect the supply and demand for goods and services, which determines prices; and how prices, in turn, determine the supply and demand of goods and services.[2][3] Macroeconomics, on the other hand, involves the "sum total of economic activity, dealing with the issues of growth, inflation and unemployment, and with national economic policies relating to these issues"[2] and the effects of government actions (such as changing taxation levels) on them.[4] Particularly in the wake of the Lucas critique, much of modern macroeconomic theory has been built upon 'microfoundations' — i.e. based upon basic assumptions about micro-level behaviour. One of the goals of microeconomics is to analyze market mechanisms that establish relative prices amongst goods and services and allocation of limited resources amongst many alternative uses. Microeconomics analyzes market failure, where markets fail to produce efficient results, as well as describing the theoretical conditions needed for perfect competition. Significant fields of study in microeconomics include general equilibrium, markets under asymmetric information, choice under uncertainty and economic applications of game theory. Also considered is the elasticity of products within the market system. Assumptions and definitions The theory of supply and demand usually assumes that markets are perfectly competitive. This implies that there are many buyers and sellers in the market and none of them have the capacity to significantly influence prices of goods and services. In many real-life transactions, the assumption fails because some individual buyers or sellers or groups of buyers or sellers do have the ability to influence prices. Quite often a sophisticated analysis is required to understand the demand-supply equation of a good. However, the theory works well in simple situations. Mainstream economics does not assume a priori that markets are preferable to other forms of social organization. In fact, much analysis is devoted to cases where so-called market failures lead to resource allocation that is suboptimal by some standard (highways are the classic example, profitable to all for use but not directly profitable for anyone to finance). In such cases, economists may attempt to find policies that will avoid waste directly by government control, indirectly by regulation that induces market participants to act in a manner consistent with optimal welfare, or by creating "missing markets" to enable efficient trading where none had previously existed. This is studied in the field of collective action. It also must be noted that "optimal welfare" usually takes on a Paretian norm, which in its mathematical application of Kaldor-Hicks Method, does not stay consistent with the Utilitarian norm within the normative side of economics which studies collective action, namely public choice. Market failure in positive economics (microeconomics) is limited in implications without mixing the belief of the economist and his or her theory. The demand for various commodities by individuals is generally thought of as the outcome of a utility-maximizing process. The interpretation of this relationship between price and quantity demanded of a given good is that, given all the other goods and constraints, this set of choices is that one which makes the consumer happiest. [edit] Modes of operation It is assumed that all firms are following rational decision-making, and will produce at the profit-maximizing output. Given this assumption, there are four categories in which a firm's profit may be considered. A firm is said to be making an economic profit when its average total cost is less than the price of each additional product at the profit-maximizing output. The economic profit is equal to the quantity output multiplied by the difference between the average total cost and the price. A firm is said to be making a normal profit when its economic profit equals zero. This occurs where average total cost equals price at the profit-maximizing output. If the price is between average total cost and average variable cost at the profit-maximizing output, then the firm is said to be in a loss-minimizing condition. The firm should still continue to produce, however, since its loss would be larger if it were to stop producing. By continuing production, the firm can offset its variable cost and at least part of its fixed cost, but by stopping completely it would lose the entirety of its fixed cost. If the price is below average variable cost at the profit-maximizing output, the firm should go into shutdown. Losses are minimized by not producing at all, since any production would not generate returns significant enough to offset any fixed cost and part of the variable cost. By not producing, the firm loses only its fixed cost. By losing this fixed cost the company faces a challenge. It must either exit the market or remain in the market and risk a complete loss. [edit] Market failure Main article: Market failure In microeconomics, the term "market failure" does not mean that a given market has ceased functioning. Instead, a market failure is a situation in which a given market does not efficiently organize production or allocate goods and services to consumers. Economists normally apply the term to situations where the inefficiency is particularly dramatic, or when it is suggested that non-market institutions would provide a more desirable result. On the other hand, in a political context, stakeholders may use the term market failure to refer to situations where market forces do not serve the public interest. The four main types or causes of market failure are: Monopolies or other cases of abuse of market power where a "single buyer or seller can exert significant influence over prices or output". Abuse of market power can be reduced by using antitrust regulations.[5] Externalities, which occur in cases where the "market does not take into account the impact of an economic activity on outsiders." There are positive externalities and negative externalities.[5] Positive externalities occur in cases such as when a television program on family health improves the public's health. Negative externalities occur in cases such as when a company’s processes pollutes air or waterways. Negative externalities can be reduced by using government regulations, taxes, or subsidies, or by using property rights to force companies and individuals to take the impacts of their economic activity into account. Public goods are goods that have the characteristics that they are non-excludable and non-rivalous and include national defense[5] and public health initiatives such as draining mosquito-breeding marshes. For example, if draining mosquito-breeding marshes was left to the private market, far fewer marshes would probably be drained. To provide a good supply of public goods, nations typically use taxes that compel all residents to pay for these public goods (due to scarce knowledge of the positive externalities to third parties/social welfare); and Cases where there is asymmetric information or uncertainty (information inefficiency).[5] Information asymmetry occurs when one party to a transaction has more or better information than the other party. For example, used-car salespeople may know whether a used car has been used as a delivery vehicle or taxi, information that may not be available to buyers. Typically it is the seller that knows more about the product than the buyer, but this is not always the case. An example of a situation where the buyer may have better information than the seller would be an estate sale of a house, as required by a last will and testament. A real estate broker purchasing this house may have more information about the house than the family members of the deceased. This situation was first described by Kenneth J. Arrow in a seminal article on health care in 1963 entitled "Uncertainty and the Welfare Economics of Medical Care," in the American Economic Review. George Akerlof later used the term asymmetric information in his 1970 work The Market for Lemons. Akerlof noticed that, in such a market, the average value of the commodity tends to go down, even for those of perfectly good quality, because the buyer has no way of knowing whether the product they are buying will turn out to be a "lemon" (a defective product). [edit] Opportunity cost Main article: Opportunity cost Although opportunity cost can be hard to quantify, the effect of opportunity cost is universal and very real on the individual level. In fact, this principle applies to all decisions, not just economic ones. Since the work of the Austrian economist Friedrich von Wieser, opportunity cost has been seen as the foundation of the marginal theory of value. Opportunity cost is one way to measure the cost of something. Rather than merely identifying and adding the costs of a project, one may also identify the next best alternative way to spend the same amount of money. The forgone profit of this next best alternative is the opportunity cost of the original choice. A common example is a farmer that chooses to farm his land rather than rent it to neighbors, wherein the opportunity cost is the forgone profit from renting. In this case, the farmer may expect to generate more profit himself. Similarly, the opportunity cost of attending university is the lost wages a student could have earned in the workforce, rather than the cost of tuition, books, and other requisite items (whose sum makes up the total cost of attendance). The opportunity cost of a vacation in the Bahamas might be the down payment money for a house. Note that opportunity cost is not the sum of the available alternatives, but rather the benefit of the single, best alternative. Possible opportunity costs of the city's decision to build the hospital on its vacant land are the loss of the land for a sporting center, or the inability to use the land for a parking lot, or the money that could have been made from selling the land, or the loss of any of the various other possible uses—but not all of these in aggregate. The true opportunity cost would be the forgone profit of the most lucrative of those listed. One question that arises here is how to assess the benefit of dissimilar alternatives. We must determine a dollar value associated with each alternative to facilitate comparison and assess opportunity cost, which may be more or less difficult depending on the things we are trying to compare. For example, many decisions involve environmental impacts whose dollar value is difficult to assess because of scientific uncertainty. Valuing a human life or the economic impact of an Arctic oil spill involves making subjective choices with ethical implications.
去抄书！找点什么资料也行
举一小例写大气压强的，应超出初中物理的知识范围，从人类对大气压强的认识，历史上的大型演示实验，大气压强的本质，托里拆利和大气压力的发现，如何确定标准大气压，大气压和天气的关系，大气压强的利用，可一直写到飞机的升力是利用气压差进行飞行的等等，就是一篇很好的论文。 参考资料 还有好多其他资料，可按照你的兴趣和感受写 大气压强·格里克及其对真空研究的贡献 大气压强·关于大气压的问答（上） 大气压强·关于大气压的回答（下） 大气压强·大气压强的本质 大气压强·标准大气压 大气压强·大气压和天气的关系 大气压强·高山反应 大气压强·潜水病与减压病 大气压强·托里拆利(1608～1647) 大气压强·奥托·格里克(1602—1686) 大气压强·十七世纪对真空问题的研究 大气压强·托里拆利和大气压力的发现 大气压强·历史上显示大气压力的大型演示实验 大气压强·伽利略狱中会徒弟 格里克市外演马戏 大气压强·各种提水机械 大气压强·负压的利用 大气压强·马德堡半球实验 大气压强·大气压强的利用 大气压强·流体压强和流速的关系 大气压强·飞机机翼的升力 大气压强·空吸现象
这个的没有免费的东西吧
美国作家爱默生说：“自信是成功的第一秘诀。”又说：“自信是英雄主义的本质。”人们常常把自信比作“发挥主观能动性的闸门，启动聪明才智的马达”，这是很有道理的。自信使你成功，自信使你的潜能充分发挥。自信心差的人往往看不起自己，同时也往往看不起别人，不能积极乐观地与人相处。显然，以这样的态度与人交往或相处，会产生种种的紧张关系，也容易被人拒绝，遭到别人的非议。而这种人际交往中的挫折或失败，又会反过来进一步打击和影响一个人的自信程度。因而，作为对自信心的培养，我们就应该改变这种不利的社会交往倾向和态度。如果我们用一种积极而乐观的、能够欣赏和赞美别人的态度与人相处的话，那么也就会在这样与人相处的情景、气氛和过程中得到一种对自我的肯定，获得别人的接受和认同。这样，我们也就能在具体的生活过程中，提高与维护我们的自信心。
好评率：90% 近年来，在各地的中考政治试题中，政治小论文已经成为一种重要的题型，因此，撰写一篇质量较高的小论文，是取得好成绩的关键。在平时的学习时，我们应加强小论文的写作训练。那么，如何才能写出一篇好的政治小论文呢？可以从以下几个方面入手： 一、了解政治小论文的几种常见题型 1、材料式。试题中给出一则或多则材料，要求围绕材料内容撰写一篇政治小论文，题目通常为自拟。 例：活动与探索题 科学技术是第一生产力，科技进步与创新是经济发展的决定性因素。教育是发展科学技术和培养人才的基础，在现代化建设中具有先导性、全局性的作用，必须摆在优先发展的战略地位。我们要大力普及科学知识、弘扬科学精神，在全社会形成崇尚科学、鼓励创新、反对迷信和伪科学的良好氛围，形成全民学习、终身学习的学习型社会，促进人的全面发展。 青年兴则国家兴，青年强则国家强。社会主义现代化需要青年去建设，中华民族的伟大复兴需要青年去奋斗。青年一代要承担起这个历史责任，就要成长为有理想、有道德、有文化、有纪律的人，成长为对党和国家、对人民有所建树的人。 之一：请结合上述材料，运用所学知识，联系实际，自拟题目，撰写一篇400字左右的政治小论文。 之二：请结合上述材料，运用所学知识，联系实际，围绕“科技·教育·人才”这一主题，撰写一篇400字左右的班会发言稿。 注意：文中不得出现本地区真实的地名、校名和人名。 2、漫画式。试题中给出一幅或多幅漫画，要求根据漫画的寓意撰写一篇政治小论文，题目一般也应自拟。 3、命题式。试题中直接给出政治小论文的题目，要求按照题目的要求撰写一篇政治小论文。 二、明确政治小论文的特点 政治小论文既不同于问答、论述题，也不同于语文作文中的议论文。但它又与问答、论述题有共同的特点，即按照“提出问题——分析问题——解决问题”的思路，解决“是什么——为什么——怎样做”的问题；与语文作文中的议论文也有共同的特点，即要做到论点、论据、论证三要素的统一。政治小论文要求我们运用思想政治课的有关知识，按照“提出问题——分析问题——解决问题”的方法，抓住论点、论据、论证三个基本要素，分析说明社会政治、经济、文化生活中的某一现实问题，它具有自己独到的特色，要求观点正确，旗帜鲜明，政治性强，要求做到论点突出，论证有力，说服力强，同时，行文要求短小精焊，结构完整，符合要求。 三、撰写政治小论文的一般步骤 试题中较经常出现的是材料式或漫画式的政治小论文，以此为例，撰写政治小论文的一般步骤有： 1、确定标题。对背景材料或漫画，我们要认真研读和领会材料的中心思想或漫画的寓意，找出其与教材知识的结合点，从中提炼出符合题意的标题。 2、提出论点。针对背景材料或漫画的寓意，开门见山，三言两语，亮明中心论点，揭出本质性的问题。论点是小论文的灵魂，一篇文章只能有一个中心论点。在确定论点时，必经回归教材，找出教材与材料主题相一致的观点。 3、分析论证。针对中心论点进行有理有据、深入本质的分析，要善于运用论据充分论证自己提出的观点。论证过程要严密，论据要充分、有力。一般说来，论据主要是理论和事实论据。理论论据来源于所学的知识，要把课本中讲述的理论知识与材料密切结合起来。 4、解决问题。针对中心论点，联系实际，提出可行性的解决办法。一般应包括两个方面：一是国家应该怎样做；二是我们中学生应该怎样做。提出的主张或措施，要符合国家的方针政策或法律法规，中学生应该怎样做应紧扣文章内容的要求，不要千篇一律。 四、熟练掌握小论文的格式及大致字数安排 一般来说，按照“提出问题——分析问题——解决问题”的思路，小论文至少应有三段，字数400字左右。第一段，提出问题，50字左右；第二段，分析问题，200字左右；第三段，解决问题，150字左右。 需要指出的是，要写好政治小论文并不是一朝一夕就能做到的，也不是临考前突击训练就是能实现的。我们在平时的学习中，要有意识地学会运用课本中“说一说”、“想一想”、“议一议”、“阅读与思考” 等小栏目以及活动课的一些材料，寻找话题，启发思维，加强小论文的写作练习，逐步提高写作技能。只要我们注重积累，熟练掌握一些写作技巧和临场窍门，在政治中考中就不难写出一篇既有独到见解、又有创新精神的优秀政治小论文。 范文：对于零花钱的看法今年来，随着人民生活水平的提高，许多家庭日益富裕起来，孩子们的零花钱便也在不止不觉间不断上涨，有的甚至到了让人膛目结舌的地步。 远的不说，就说我们班吧！班里有些男生女生，学习成绩不怎么样，可是对于穿着打扮，可都是“行家”。“BALENO“的上衣，“NIKE“的鞋子，“adidas“的书包，“SONY”的MP3……真可谓集名牌于一身。另有一些男生，通常每天身上都会带有上百块的钱，用于所谓的“吃喝玩乐”，泡网吧，打游戏，结交不良少年；更有的已经拥有了自己的手机……这种例子在如今的校园中已不再是凤毛麟角了。 为什么会出现这样的情况呢？我认为，之所以造成这种情况，有以下几点原因：一，人民生活水平提高，家庭经济状况与之前相比有了较大改善；二，目前家庭多是独生子女，父母过分溺爱；三，社会不良风气的影响。而其中家长对孩子的过分溺爱是最主要原因。在中国的家庭教育传统中，父母们都会用零花钱来培养孩子良好的行为习惯和思想观念，比如：勤俭节约、财务自理。但在今天，生活富裕了，孩子的那点零花钱家长也不会放在心上。但这种超前消费意识是不适合中学生的，将给他们带来诸多不良影响。 其次，孩子之间容易产生攀比心理，从而引发一些孩子的心理失衡。今天你在“肯德基”搓一顿几十元；明天我在“XX酒家”摆一桌几百元，看谁更有风度。现在的孩子谁手里要是没几个零花钱，看着同伴经常拿着钱去买这买那，总是羡慕得很，又尴尬的很。这种羡慕、尴尬处理得好那是幸运，若是处理得不好，带来的后果将不可想象。4月12日江北区一名约7岁的女孩哭喊着要跳楼。不为别的，就只是为了从父母那得到零花钱。而有的孩子可能萌生或多或少的拜金主义，以金钱或能换取金钱的一切作为自己的钟爱。 第四，会使孩子形成错误的金钱观，以为“金钱是万能的”，“有钱能使鬼推磨”，不知道应认真学好知识，不懂得承担起自己应负的责任。有的孩子，把父母的叮咛嘱咐，老师的教诲当成“耳边风”，只懂得吃喝玩乐，腹中却空空如也。更是忘却了将来有独立生活，赡养父母，为社会作贡献的责任。 最后。也是最严重的，可能会导致某些孩子走上犯罪之路。所谓“由俭入奢易，由奢人俭难。“可能今天你的家庭是相对富裕的，但谁也不能保证将永远富有，倘若已经养成了奢侈的习惯，将来要如何面对贫穷呢?也许有的人靠自己的意志能熬过去，但有的人却会难以自拔。前不久，报纸曾经报道，广州一名14岁的中学生在潜入同字家中盗窃被发现后，向同学的母亲狂刺38刀实在是惨无人道。 身为父母，谁不爱自己的孩子，谁不愿给孩子付出呢?但是，家长们该给孩子什么?这是一个值得深思的问题，一味地给钱显然是错误的，而应该给他们以知识和正确的引导。金钱是把双刃剑，用得不好就伤人———家长们对此一定要有充分认识。。
写作思路：把你对环保的看法写出来。
政治小论文《我看环保》
环境问题不仅是个生活质量问题，更是一个直接影响人尖生存与发展的大问题。(提出论点)
我们不得不承认，环境保护已迫在眉睫。环保虽如此重要，国家也颁布了一系列保护环境的法律和法规，可是在社会上仍有一些人，为了个人的利益去破坏环境，有的救灾屡禁不止。这就要求我们采取措施进一步提高人们的环保意识，依法规范人们的行为。(分析论点)为此，我特提出如下建议：(解决论点)
首先，应在学生中普及环保教育，开设环保科目，并规定为必修课。规定每个学生必须对环保作出贡献。如规定每个学生一年必须种一棵树等，从而让每个学生都明白：对于环保，自己也有一份责任，自己也应该出一份力。
其次，国家有关部门应不定期对各个单位进行突击检查，对那些违反有关环保方面的法律和法规的单位实施重罚，并对其进行思想教育。这样才能从污染源上加以控制、治理。
再次，对在环保方面作出突出贡献的单位、个人，应在物质和精神上给予奖励。这样能更有效地调动人们的积极性，这对于全民参加环保会有一定的促进作用。
最后，国家应拨款建一些环保设施，如建一些污水处理站，保证流入江海湖泊的水的质量;采取“垃圾分类回收”措施，并在行动之前加以宣传，以得到群众的积极响应。
环保问题的确应该引起我们每个人的重视。每个人都应该思考，自己应该为环保做点什么。愿人人都为环保出一份力，让美好的环境永远伴随着我们!(联系实际,表明观点)
评价:本文侧重解决环境问题,特点是将分析问题结合到解决问题的过程中。
绿色环保作文200字 （一） 先如今环保已经成为了我们必做的事，因为现在地球上的环境正受到威胁。 现在，我们知道地球已经开始变暖，寒冷地方的冰已经开始融化，变成的水使水平面越来越高，让许多沿海的国家被淹没。更多的土地沙漠化，天灾不断来袭，使我们的生活不再那么无忧无虑。 首先，我们必须从身边做起。 大片森林被不断砍伐，汽车尾气不断排放……这些首先就会直接影响到我们的生活，因为这些让我们“不敢呼吸”。所以，这些问题最好的解决方法就是少开车，多骑自行车，而且，骑自行车也很有益身体健康！。可虽然一直这样说，而且说了也不只一次，可为什么还是有那么多的车在路上呢？所以，这个方法实在，有点不实用。 最简单的就是种树了，树是人类的好朋友，他们能帮助人类许多事，比如净化空气啦，等等。所以，多种树，这个方法很实用！ 总而言之，我们的地球要我们自己去爱护，去保护，要用实际行动来帮助地球，让环境更美好！ 绿色环保作文200字 （二） 先如今环保已经成为了我们必做的事，因为现在地球上的环境正受到威胁。 现在，我们知道地球已经开始变暖，寒冷地方的冰已经开始融化，变成的水使水平面越来越高，让许多沿海的国家被淹没。更多的土地沙漠化，天灾不断来袭，使我们的生活不再那么无忧无虑。 首先，我们必须从身边做起。 大片森林被不断砍伐，汽车尾气不断排放……这些首先就会直接影响到我们的生活，因为这些让我们“不敢呼吸”。所以，这些问题最好的解决方法就是少开车，多骑自行车，而且，骑自行车也很有益身体健康！。可虽然一直这样说，而且说了也不只一次，可为什么还是有那么多的车在路上呢？所以，这个方法实在，有点不实用。 最简单的就是种树了，树是人类的好朋友，他们能帮助人类许多事，比如净化空气啦，等等。所以，多种树，这个方法很实用！ 绿色环保作文200字 （三） 前段时间，我在家里的电视上看到工厂排出了很多浓烟。我感到非常痛心。 我们的地球严重被污染了。天空上，因为工厂大量的排放出浓烟，废气，汽车的尾气大量的排出，湛蓝湛蓝的天空变成了黑色。小河里的水，因为人们在那里洗衣服，工厂里排出大量的废水，河边还堆有很多的垃圾，小河的水本来是清澈见底的，可是现在却变成了又黑又臭的污水。( )森林，因为人们不但不保护森林，还乱砍滥伐茂密的森林，森林就这样的消失了。现在每家每户都还用着塑料袋，造成了严重的'白色污染。据科学家分析，这种白色污染一千年也不会消失。 保护环境，刻不容缓！因为保护环境就是在保护自己啊！ 绿色环保作文200字 （四） 保护环境就是保护地球还是间接的保护我们人类自己，如果环境被破坏的话，那么我们赖以生存的家园就很有可能被沙漠吞噬 ! 我在这里向全世界的人们呼吁 保护环境人人有责 ! 如果我们还在这样的破坏环境的话，我们的家园即将遭到崩溃 。 那时我们便没有去处了， 保护环境人人有责 ， 从小事开始作起吧， 如我们不乱扔垃圾， 随地吐痰等。 保护环境人人有责！ 绿色环保作文200字 （五） 同学们，我们是21世纪的主人，环保意识是现代人的重要标志。我们应当切实地树立起时代责任感。心系全球，着眼身边，立足校园。多弯弯腰捡捡果皮纸屑，首先是不要随地乱扔乱丢；多走几步，不要穿越绿化带，践踏绿地。“勿以善小而不为，勿以恶小而为之”，从我做起，从小做起，从身边做起，从现在做起。保护地球母亲，净化绿色校园。 让我们的校园更加美丽吧！