四、情态动词must用法详解
1) must表示必须，否定回答时用needn’t. mustn’t表示不许可。
【例如】
You must get to the station before 3, otherwise you will miss the train.Must I hand in my homework tomorrow?
No, you needn’t. You can turn it in the day after tomorrow.
You mustn’t smoke in the hospital.
2) must用于肯定句，可以表示推测，翻译为：一定或想必。后面接动词的一般时，表示对现在的推测，接动词的完成式，表示对过去的推测。对过去的推测是考试的重点。
【例如】
She must live near here, for she comes to work on foot.
She was absent from class. There must have been something wrong with her.
The light was out. They must have gone to bed.
Mary’s score on the test is the highest in her class. She ____ have studied very hard.
A) may B) should C) must D) ought to
"must +不定式完成式"表示对过去发生事情的推测。题意为：玛丽的考试成绩全班第一，她学习一定很刻苦。答案为C.
五、情态动词shall的用法
shall用于第二、三人称，表示许诺、答应、命令等。
【例如】
If he passes the exam he shall have a holiday.
The law shall comes into effect on May 1st.
六、will与would用法辨析
1) will作情态动词，表示意愿、习惯等。would表示过去的习惯。
【例如】
It will be highly appreciated if you will send us your latest price list.
On Sundays he would get up early and go fishing.
2) Will/would you please do...,Would you like to do...,Would you mind doing...
都表示建议、询问、请求等。
【例如】
Will you please pass me a cup of tea?
Would you like me to give you a hand?
This box is too heavy, ____give me a hand?
A) would you mind B) would you please
C) will you like to D) will you please to
四个结构中，would you mind接动名词;would you please接动词原形;
will you like to不是正确结构;will you please to也不是正确结构，因此答案为B。
