4．表示请求或规劝。You might pay more attention to me．

5．"may(might)+have+过去分词"表示对过去发生的行为的推测。例如：

　He may not have finished the work．

6．May/might的其他用法：①may not表示一种礼貌的"不可"。如：

　You may not leave the thing half done．

②．might可表示忠告，责备。如：

Yon have broken two dishes．You might try to be more careful．

③．may well +原形， 理所当然

You may well say so．你当然可以这样讲。

④．May/might as well=had better 最好 如：We may as well stay where we are．我们最好是留在原处。 If that is the case, we may as well try.

⑤．May/might as well+原形+as+原形 与其......不如； 最好......不要；如：You might as well throw your money away as lend it to him．你要借给他钱,不如把钱扔了。

Peter ___come with us tonight, but he isn't very sure yet.

　 A. must　　B. may　 C. can　 D. will

四。 have to和must

1. must表示必须，强调的是一种主观看法。也表示责任或义务．而have to表示必须时强调的是客观需要。have to可以用在更多的时态中。

My brother was very ill, so I had to call the doctor in the middle of the night.　我弟弟病得很厉害，我只得半夜里把医生请来。(客观上需要做这件事)

He said that they must work hard.他说他们必须努力工作.（主观上要做这件事） You must obey the rules．(责任或义务)

You will have to do it again．你将不得不再做一次。

回答must引出的问句时．如果是否定的回答．不能用mustn't．而要用needn't或don't have to。如： Must we hand in our exercise books today?

Yes．you must．(No．you don't have to．)

2． "must be+表语"的结构表示推测。它的否定或疑问形式用can代替must。

　　This must be your pen．

3．must+have+过去分词"的结构常用在肯定句中．表示对过去发生的行为的推测。它的否定或疑问形式用can代替must。

He must have been to Shanghai．

4 .must一般只表现在，have则有更多的时态形式。

5.二者的否定意义不大相同．Mustn't表"禁止", don't have to(=needn't)表没有必要。例如： Yon mustn't go．你可不要去。

You don't have to go．你不必去。

6．询问对方的意愿时应用must。例如： Must I clean all the room?

五． will和would

1. 表示请求、建议等，would 比will委婉客气. Would you pass me the salt?

2．表示意志、愿望和决心。I will never do that again.

　They asked us if we would do that again.

3．表示习惯动作。 Fish will die without water.

4．表示预言。Oil will float on water．

5．用"will be"和"will十have十过去分词"的结构表示推测，主要用于第二、三人称。前者表示对目前情况的推测，后者表示对已经完成的动作或事态的推测。This will be the book