must只用于肯定句中。
can/could不能用语肯定句中。
may/might不能用语疑问句中。
另外还应注意can’t表示不可能，may not表示可能不。
考试时，如果有原因说明自己的猜测，一般应该must, can’t用而不是may, may not。如：
He can’t have stolen the money; he is not such kind of person.
Some pleasant thing must have happened to him. He is so excited.
3） 注意推测性用法中谓语动词发生的时间。
如果推测的为过去的事情，情态动词后则用完成形式。
There must have been no one in, for nobody answered the phone.
如果推测的是正在进行的事情，情态动词后则用动词的进行形式。
They must be talking about something very secret.
如果推测的是现在的状态等，情态动词后则用原形动词
He must be badly ill. He looks so pale.
如果推测的是将来发生的事情，情态动词后同样用原形动词，这时，情态动词只能是may/might。
There may be a terrible storm in the following few days.
4） 注意情态动词+动词的完成形式所表达的意思与题干意思是否相符。
其它情态动词+ 动词的完成形式并不表示推测，而分别表示：
could have done本来能够
He didn’t take part in the competition, he _______ though.
A. won B. didn’t win C. could win D. could have won
needn’t have done 本来没不要
You ________. There was plenty of time.
A. needn’t hurry B. can’t hurry
C. mustn’t have hurried D. needn’t have hurried
should/ought to have done 本来应该
You _______ me earlier. I could have helped you.
A. should tell me B. should have told
C. need to tell D. needn’t have told
shouldn’t/oughtn’t to have done 本来不应该
You ____ him so closely; you should have kept your distance.
A. shouldn’t follow B. mustn’t follow (2000.6)
C. couldn’t have been following D. shouldn’t have been following
might have done 本来应该（用来表示一种责备）
You ______ even though you were busy at that time.
A. might help him B. must have helped him
C. might have helped him D. should help him
这类题在设计干扰项时，一般都会有情态动词推测性用法的涉及，同学们应注意分词上下文的逻辑和语意关系。
5） 注意常用情态动词的基本句法和表意功能
其它常用动词的用法，如shall表示命令、威胁、许诺或征求许可，may/might as well等，同学们都应多多注意其用法。
四、 倒装
倒装结构也是比较常见的一种句式，但考查的分量不大，考试都有哪些特点，如何应对，首先让我们一起来看一下近几年的考题。
1．Test Yourself.
1) I could not persuade him to accept it, ___ make him see the
importance of it.(19995.1)
A. if only I could not B. no more than I could
C. or I could not D. nor could I
2) Not until the game had begun ______at the sports ground.(2000.6)
A. had he arrived B. would he have arrived
C. did he arrive C. should he have arrived
3) The organization had broken no rules,
but _____ had it acted
responsibly.(19996.1)
A. neither B. so C. either D. both
4) We have been told that under no circumstances ______ the telephone
in the office for personal affairs.(1999.6)
A. may we use B. we may use C. we could use D. did we use
5) Only under special circumstances_____to take make-up tests.(1997.6)
A. are freshmen permitted B. freshmen are permitted
C. permitted are freshmen D. are permitted freshmen
参考答案：
1) D 2) C 3) A 4) B 5) A
2．倒装测试范围和应对策略
倒装分部分倒装和全部倒装，但从近几年的测试来看，重点是部分倒装。对于倒装句型同学们所应注意的就是在哪些情况下需要倒装，并且如何倒装。注意下面常见的倒装条件。
1） 含有否定意味的词置于句首，主谓倒装。
同学们应注意常用否定词语，如：hardly, barely, not, seldom, little, few, nowhere, never, at no time, by no means, in no way, in no case, under no circumstances, not until, not only…
but also.., neither … nor…等。如果是在从句的句首，则从句倒装，如4）题。
2） only + 状语置于句首，主谓倒装。
Only后的状语可以是单词、短语，也可以是从句，要特别注意，从句并不倒装，而是主句倒装。如：
Only when the war was over was he able to get happily back to work.
3） Neither/So置于句首倒装，表示也/也不……，如上面的2）3）题。
4） There/here/then或做状语的地点副词和地点介词短语置于句首，要全部倒装。如：
There stands a monument in the center of the square.
Down came a light form the ceiling when he was walking across the floor.
On the hay lay a wounded boy of not more than seventeen.
5） 现在分词和过去分词可提至句首构成分词+ be + 主语+其它+的倒装句式。如：
Enclosed in the letter was a photo of a beautiful
girl.
Glooming in the test tube on the table was the mysterious something which they had been working so hard to find, radium.
6） so/such…. that句型中，so + 形容词/副词提前，主谓倒装。如：
So boring was the speech that the audience all left halfway.
Such a noise did they make that the neighbors could not go to sleep at night.
