楼主,请你不要相信 『海很深梦很真』 的回答 她全都是机器翻译的,完全不对,害人不浅啊 在文中第一次出现 : ① when the word first appeared in the ② when the word was first used in the paper 这些缩写第一次出现时,我做了解释 : ① I explained what the abbreviations meant when the word first appeared in the ② I explained what the abbreviations meant when the word was first used in the 这两种说法都可以 ~ ♥ 自己认真翻译的,应该比较地道,敬请采纳、