be的用法
现在时I am, you are, 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
1.be +现在分词,构成进行时态,例如:
They are having a meeting.他们正在开会。
2.be+过去分词,构成被动语态,例如:
The window was broken by Tom.窗户是汤姆打碎的。
3.be+动词不定式,可表示下列内容:
a.表示最近、未来的计划或安排,例如:
He is to go to New York next week.他下周要去纽约。
说明:这种用法也可以说成是一种将来时态表达法。
b.表示命令,例如:
You are to explain this.对此你要做出解释。
c.征求意见,例如:
How am I to answer him?我该怎样答复他?
d.表示相约、商定,例如:
We are to meet at the school gate at seven tomorrow morning.我们明天早晨7点在校门口集合。