情真意切的情态动词

语言是用来交流的工具，情态动词反映的是说话人在交流过程中的态度和情感。因此，正确使用情态动词很重要。

一、考查推测的情态动词常见有must，ought to，should，can，could，may，might等

（一）对现在动作或状态的推测（以上情态动词+be/do）

1. Liza________well not want to go on the trip—she hates traveling.

2. You________be hungry already—you had lunch only halfan hour ago.

3. It is usually warm in my hometown in March， but it________be rather cold sometimes.

4. —Hows your tour around the North Lake？Is it beautiful？

—It________be， but it is now heavily polluted.

5. —Ive taken someone elses green sweater by mistake.

—It________Harrys. He always wears green.

6. —Look， it________be Mr.Zhang.

—No， It________be him. He has gone to Wuhan.

7. Mr.Brush is on time for everything. How________it be that he was late for the opening ceremony？

?点拨?从表示推测的语气强弱程度而言：

1. must语气最强，表示“一定，肯定，准是”，只用于肯定句;

2. ought to/should语气次之，译为“应该会，很可能会”，指按常理推测，如：He has learnt to play the piano for three years. He should play the piece of music very well.

3. may，might，could这三个词语气较弱，译为“也许，可能”，句中常有or…or，Im not sure等信息提示，常用于肯定句或否定句如：He may be asleep or may have gone out， I am not sure.

4. can表示推测常用于否定句和疑问句，表示“不可能”，有时也用于肯定句，表示客观上有某种可能，如：Anyone can make mistakes.

（二）对过去动作或状态的推测（must/may/can/could/might+have done）

1. She________have left school， for her bike is still here.

2. —I cant find my purse anywhere.

—You________have lost it while shopping.

3. —She looks very happy. She________have passed the exam.

—I guess so. It is not too difficult after all.

4. —Where is my dictionary？I remember I put it here yesterday.

—You________it in the wrong place.

?点拨?1.“should（not）/ought（not）+have done”不表示对过去的推测，而表示虚拟语气，即“过去本应该做某事却没做或过去本不应该做某事却做了”，有一种责备的口气。

2.“might（not）/could（not）have done”有兩层含义：第一、表示对过去的推测，相当于may/can have done;第二、表示虚拟语气，即“过去本可以做某事却没做或本不可以做某事却做了，

例如：①—Im sorry. I________at you the other day.

—Forget it. I was a bit out of control myself.

A. shouldnt shout B. shouldnt have shouted

C. mustnt shout D. mustnt have shouted

②—Ill tell Mary about her new job tomorrow.

—You her last week.

A. ought to tell B. would have told C. must tell D. ought to have told

③Thank you for your hard work last week. I dont think we________it without you.

A. can manage B. could have managed

C. could manage D. can have managed

二、情态动词的其他用法

（一）can，could，may和might的其他用法以及be able to

1. You dont have to know the name of the author to find a book. You________find the book by the title.

2. A computer________think for itself;it must be told what to do.

3. —Could I call you by the first name？

—Yes， you________.

4. The fire spread quickly. Fortunately， everyone in the fire________escape from it.

5. —May I smoke here？

—If you________， choose a seat in the smoking section.

[點拨]1. can，could，may，might还可以表示“请求，许可”，could和might在疑问句中表示更加委婉的语气，对于can，could，may，might疑问句的肯定答复用can/may，或if you must，否定答复用mustnt，cant，may not或Sorry，youd better not，但不能用could（not），might（not）回答。

2. can表示能力，译为“会，能”，could是过去式。be able to表示有能力并成功地完成，而且可构成多种时态，如：After finishing his courses， he will be able to speak French well. Im sorry I havent been able to answer your letter.

（二）must和have to

1. —Must he come to sign this paper himself？

—Yes， he________.

2. Jack， look at the clock， ________you play at such later hour？

3. Some aspects of a pilots job________be boring， and pilots often________work at inconvenient hours.

[点拨]must表示必要性，译为“必须，一定”，否定句mustnt表示绝对禁止。have to表示“必须做，不得不做”，着重于客观需要，而must表示主观需要。另外，have to还可用于多种时态。

（三）will，would，shall，should，ought to，had better

1. John promised his doctor he________not smoke， and he has never smoked ever since.

2. —Mr.Gordon asked me to remind you of the meeting this afternoon. Dont you forget it？

—OK， I________.

3. —What does the sign over there read？

—No person________smoke or carry a lighted cigarette， cigar or pipe in this area.

4. —The room is so dirty. ________we clean it？

—Of course.

5. —Excuse me， but I want to use your computer to type a report.

—You________have my computer if you dont take care of it.

6. According to the air traffic rules， you________switch off your mobile phone before boarding.

7. Its freezing outside. You________put on your overcoat.

[点拨]1. will表示请求或建议，常和第二人称连用，would更委婉。will和would还可以表示说话人的意愿和决心，常和第一及第三人称连用，would表示过去。will和would表示习惯性动作或某种倾向，would为过去时态，常译成“总是”。如：Fish will die without water. My grandpa would talk to us for hours if you give him the chance.

2. shall用于第一人称或第三人称的疑问句，表示征询对方意见。shall用于第二、三人称，表示说话人给对方的许诺、命令、警告、威胁。shall用于第三人称的条约、规章、法令等文件中，表示义务，意为“应该”。

3. should和ought to表示义务，意为“应该”，ought to比should语气更强烈。

4. had better（not）do表示“最好做/不做”，经常用于提出建议。

（四）need和dare

1. I neednt telephone him， for I will visit him soon.

2. —Need I go there now？

—No. You neednt. /—Yes. You must

3. The desk needs to be repaired.

4. Dare you go home alone at eleven in the evening？

5. He is a brave boy and dares to catch a snake.

6. Do you dare（to）swim in the river？

[点拨]1. need表示“需要”，作为情态动词只用于否定句或疑问句。对于need疑问句的肯定答复和否定答复和must一样，肯定答复用must，否定答复用neednt或dont have to。need作为实义动词，表示需要，可用于任何句型中，后面可以接名词、代词、不定式或动名词。

2. “neednt have done”表示“本不需要做某事却做了”，是一种虚拟语气的表达。

3. dare表示“敢”，作为情态动词，通常用于否定句、疑问句或条件从句中;作为实义动词，在肯定句中要接to，在否定句或疑问句中可省略to。