谭维维腿照:1.be动词在什么情况下要加?2.什么时候加"be"

英语的“be”是个特别动词；有些语言，如中文和马来文，并没有“be”这样的动词。
“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”, 但这并不是标准英语。
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：
9. Her money in the drawer was stolen.
20. A number of good jobs are taken up byforeigners.
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?

1.be首先得明白它是一个动词,称为be动词,中文意思通常为"是"
Eg:I am a student. 我是一个学生.
而像run,jump,read这些是行为动词,又称实义动词.
在一句句子中,如果你要使用be动词,那么行为动词就只能用ing形式,
Eg:I am running. 我正在跑步.
而如果你不用be动词,那么行为动词也就不能变为ing形式.
Eg:I read a book.

2.再有些单词或词组后面只能加动词原形，
Eg:to,don't,can,should,
而如果你要在它们后面加be动词的话，就不能加am,is,are,要加be.
Eg:I should be at home now.
或者在祈使句中
Eg:Don't be late again.