be动词的用法
在英语语法中，be动词意思和用法很多，一般的意思是：是，此种用法，有多种变化形式，is，am，are，was，were，being，been，to be.另外，be动词还有成为的意思。根据句子中不同的人称、数和时态，应该选择相应的be动词。
be (be/is/are/am/was/were)
[bi:]
vi
he is, we are, you are, they are (缩略式 I'm, you're, he's, we're, you're, they're), (否定缩略式 I'm not, isn't, aren't), 过去时 I was, you were, he was, we were, you were, they were (过去时否定缩略式 wasn't, weren't),过去分词been,现在分词being
英语的“be”是个特殊动词;有些语言，如马来文等，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)
【当做主动词时，“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：
The man is a science teacher.
这个男子是一位科学教师。
Mary's new dressesare colourful.
玛丽的新衣服色彩鲜艳。
I havebeen there before.
我以前去过那里。
My motheris in the kitchen now.
我妈妈现在在厨房里。
★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：
Is the man a science teacher?
Are Mary's new dresses colourful?
Have I been there before?
Is mother in the kitchen now?
★当“be”要在祈使句中出现时，陈述句可借助助动词“do”，否定句必须在前加上助动词“don't”，如：
Don't be silly!
Do be obedient!
Be careful!
Don'tbe a fool!
★“Be”有两种缩写法，如下：
He's not...../He isn't....
You're not...../You aren't...
★但“am + not”的缩写法只有一个：
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
【1.】“Be + 现在分词”以组成进行式时态(Continuous Tenses)，如：
Tony's maidis washing his new car.
The children are playing in the field.
Samuelwas eating when I came in.
We havebeen living here since 1959.
【2.】“事/物人 +Be + 过去分词”以组成被动语态(The Passive Voice),如：
Her money in the drawer was stolen
A number of good jobs are taken up by foreigners
David studied in Taiwan but hasbeen trained as a language lecturer in America
Can all the wonderful birds be found in our Bird Park
The disobedient boywas told to stand out- side the classroom
Steps are being taken to reduce traffic con- gestion during peak hours
Dishonest students will be immediately dealt with