动词"be"的用法
“Be”除了原形的“be”之外,还有另外七种形式：am, is, are, been, being, was, were.
在句子中,“be”可以是主动词(The Principal Verb)或助动词(The Auxiliary Verb).
当主动词时,“be”在性质上属于接系动词(The Linking Verb), 后面要有名词、形容词、地方副词或短语作补足语(The Complement).例如：
1. The man is a science teacher.
2. Mary's new dresses are colourful.
3. I have been there before.
4. Mother is in the kitchen now.
这四个都是陈述句,可以变成疑问句,方法简单,把主语和“be”或助动词对换位置即可：
5. Is the man a science teacher?
6. Are Mary's new dresses colourful?
7. Have I been there before?
8. Is mother in the kitchen now?
当“be”要在祈使句中出现时,它必须借重助动词“do”或“don't”之助,如：
9. Don't be silly!
10. Do be obedient!
11. Don't be a fool!
“Be”有两种缩写法,如下：
12. He's not./He isn't.
13. You're not./You aren't...
但“am + not”的缩写法只有一个：
14. I'm not.
有人用“ain't”(ain't等价于is not,are not,am not), 但这并不是标准英语,只是一种比较口语化的说法.
谈过了“be”作主动词的功能,现在看看“be”作助动词时,有些什么用法：
1.“Be + 现在分词”以组成进行式时态(Continuous Tenses),如：
15. Tony's maid is washing his new car.
16. The children are playing in the field.
17. Samuel was eating when I came in.
18. We have been living here since 1959.
2.“Be + 过去分词”以组成被动语态(The Passive Voice),如：
19. Her money in the drawer was stolen.
20. A lot of good jobs are taken up by foreigners.
21. David studied in Taiwan but has been trained as a language lecturer in America.
22. Can all the wonderful birds be found in our Bird Park?
23. The disobedient boy was told to stand outside the classroom.
24. Steps are being taken to reduce traffic congestion during rush hours.
25. Dishonest students will be immediately dealt with.