be的用法与作用?

Question

be的用法与作用?

Answer 1

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.
English is becoming more and more important.英语现在越来越重要.
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.
English is taught throughout the world.世界各地都教英语.
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.
We are to teach the freshpersons.我们要教新生.
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.
He is to come to the office this afternoon.要他今天下午来办公室.
c.征求意见,例如：
How am I to answer him?我该怎样答复他?
Who is to go there?谁该去那儿呢?
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.