双引号和单引号都有。双引号(1)表示文中的人说的话。"I've been thinking about this afternoon, you know,"said Halliday rather (2)引用单词或短语。How do you spell the word "across"?(3)不寻常的词语也常用引号,以引人注意。The noun to which a relative pronoun refers is called the "antecedent" of the 关系代词所指代的名词唤作关系代词的“先行词”。(4)书名和诗文名也用引号。Have you read, “The Jungle"?你读过《屠场》吗? 单引号 这两种引号没什么区别,但双引号更通用。单引号似多用在英国。She enjoyed the film 'Madame curie'她很欣赏影片《居里夫人》。(英国习惯)She enjoyed the film "Madame C" (美国习惯)