##### 助动词
- 助动词 `Auxiliary Verbs`
- 助动词是一类用于构成各种时态, 语态和语气的动词, 通常与主要的实义动词一起使用, 形成谓语动词
- 分类
- be (用于[[英语时态|进行状态]], [[英语语态|被动语态]], [[疑问句]])
- She is reading a book. (她正在读一本书)
- The book was written by Mark Twain. (这本书是由马克·吐温写的)
- have (用于[[英语时态|完成状态]], [[疑问句]])
- They have finished their homework. (他们已经完成了作业)
- We haven’t been to the cinema for ages. (我们好久没去看电影了)
- do (用于[[否定句]], [[疑问句]], [[强调句]])
- He doesn't like coffee. (他不喜欢咖啡)
- Do you play the piano? (你会弹钢琴吗)