A． 动词be\ intend\ mean\ plan\want\ hope等的过去式，后接动词不定式完成式（即：eg: mean-meant to have done），表示过去想做而没有做的事情；而动词be\ intend\ mean\ plan\want\ hope等的完成式，后接动词不定式（即：eg: mean-have meant to do）,也表示过去想做而没有做的事。

Eg: I intended to have attended the meeting, but I was ill.

= I have intended to attend the meeting, but I was ill.

B. even if\ even though 引导让步状语从句，若要表示与现在情况相反，从句要接"(may\ might) + do"; 若要表示与过去情况相反，从句要接"had done"; 类似的词还有：though\ as though \ so long as \ no matter what \ whatever \ whoever, etc.

Eg: However dangerous it might be, he would have a try.

Even though I had been busy then, I would have helped you.

C. live 用在"long live"中-Long live the people! (人民万岁！)

D. may 用在句子开头表示"祝愿"-May you succeed.\ May you be happy.!

【知识反馈】完成下列习题和练习册中对应的习题。　

1.The two students talked as if they _____ friends for years.

A. should be　B. would be C. have been　　D. had been

2.It is important that I _____ with Mr. Williams immediately.

A. speak　　　 B. spoke C. will speak　　D. to speak

3.Let's say you could go there again, how _____ feel?

A. will you　 B. should you C. would you　D. do you

4.I can't stand him. He always talks as though he____

everything.

A. knew 　B. knows C. has known　　D. had known

5._____ the fog, we should have reached our school.

A. Because of　 B. In spite of C. In case of　　D. But for

6.I would have told him the answer had it been possible, but I _____ so busy then.

A. had been　　　B. were C. was　　 D. would be

7.He's working hard for fear that he _____.

A. should fall behind　 　B. fell behind

C. may fall behind　 D. would fallen behind