39.助动词be 与have
i.be作为助动词可以：
1.构成进行时态(be+现在分词)
i am seeing a friend off.
我在给一个朋友送行。
she was telling us a story.
她在给我们讲故事。
he will be leaving tomorrow．
他明天走。
what have you been doing these days?
这些时候你都在干什么?
2.构被动语态(be+过去分词)：
these books were published last year.
这些书是去年山版的。
rice is grown chiefly in the south.
水稻主要在南方种植。
the houses are being rebuilt．
这些房了正在重建。
the plan has been approved．
计划业已批准。
此外还可以和不定式构成复合谓语表示打算做或应该做的事：
where are we to meet?
我们在哪里碰头?
who is to pay?
谁付钱?
you're to be back tonight．
你应今晚回来。
the worst was still to come．
最糟糕的情况还在后头。
ii.have作为助动词可以：
1.构成完成时态(have+过去分词)：
what has happened?
出了什么事?
he told me jane had left．
他告诉我简已经走了。
she will have arrived by this time tomorrow.
明天这时她就会到了。
how long have you been there?
你在那里待了多久?
2.构成完成进行时态（have+been+现在分词)
we have been trying to contact you．
我们一直在想和你联系。
she has been teaching there for thirty years．
她在那里任教达三十年。
that was the book he had been looking for.
这是他一直在找的书。
另外，have (got)to还可构成谓语，表示“不得不”：
we have (got) to be careful．
我们得小心。
you don't have to worry．
你不必忧虑。