be动词后面的动词形式有三种可能:
-ing:
现在进行时, I'm trying to give you the right answer.
-ed:
被动语态, I'm told that you don't know her.
to do:
1.表示按计划或安排要做的事。例如:
They said goodbye, little knowing that they were never to meet again.他们告了别,不知道以后再也不会见面了。
2.表示“应该”,相当于should, ought to。例如:
You are to report to the police.你应该报警。
3.表示“必须”,相当于must, have to。例如:
The letter is to be handed to him in person.这封信必须亲手交给他。
4.表示“想,打算”,相当于intend, want。例如:
If we are to be there before ten, we’ll have to go now.如果我们要在十点前到,我们现在就得走。
5.用于
第一人称疑问句,表示征求对方意见。例如:
6.用于否定句,表示“禁止”,相当于mustn’t。例如:
You are not to smoke in the reading-room.你不可以在阅览室里吸烟。
7.表示“可以,可能”,相当于may, can。例如:
The news is to be found in the evening paper.这条消息可以在晚报上见到。
8.were to do sth.用于if或even if / even though
从句中,表示对未来的假设。例如:
9.be to blame(该受责备,对某坏事应负责任)与be to let(待出租)两种结构中,用不定式的主动形式表示被动含义。例如:
This house is to let.这房子要出租。