語言是用來交流的工具，情態(tài)動(dòng)詞反映的是說話人在交流過程中的態(tài)度和情感。因此，正確使用情態(tài)動(dòng)詞很重要。

一、考查推測(cè)的情態(tài)動(dòng)詞常見有must，ought to，should，can，could，may，might等

（一）對(duì)現(xiàn)在動(dòng)作或狀態(tài)的推測(cè)（以上情態(tài)動(dòng)詞+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？

?點(diǎn)撥?從表示推測(cè)的語氣強(qiáng)弱程度而言：

1. must語氣最強(qiáng)，表示“一定，肯定，準(zhǔn)是”，只用于肯定句;

2. ought to/should語氣次之，譯為“應(yīng)該會(huì)，很可能會(huì)”，指按常理推測(cè)，如：He has learnt to play the piano for three years. He should play the piece of music very well.

3. may，might，could這三個(gè)詞語氣較弱，譯為“也許，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表示推測(cè)常用于否定句和疑問句，表示“不可能”，有時(shí)也用于肯定句，表示客觀上有某種可能，如：Anyone can make mistakes.

（二）對(duì)過去動(dòng)作或狀態(tài)的推測(cè)（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.

?點(diǎn)撥?1.“should（not）/ought（not）+have done”不表示對(duì)過去的推測(cè)，而表示虛擬語氣，即“過去本應(yīng)該做某事卻沒做或過去本不應(yīng)該做某事卻做了”，有一種責(zé)備的口氣。

2.“might（not）/could（not）have done”有兩層含義：第一、表示對(duì)過去的推測(cè)，相當(dāng)于may/can have done;第二、表示虛擬語氣，即“過去本可以做某事卻沒做或本不可以做某事卻做了，

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、情態(tài)動(dòng)詞的其他用法

（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(diǎn)撥]1. can，could，may，might還可以表示“請(qǐng)求，許可”，could和might在疑問句中表示更加委婉的語氣，對(duì)于can，could，may，might疑問句的肯定答復(fù)用can/may，或if you must，否定答復(fù)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，譯為“會(huì)，能”，could是過去式。be able to表示有能力并成功地完成，而且可構(gòu)成多種時(shí)態(tài)，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.

[點(diǎn)撥]must表示必要性，譯為“必須，一定”，否定句mustnt表示絕對(duì)禁止。have to表示“必須做，不得不做”，著重于客觀需要，而must表示主觀需要。另外，have to還可用于多種時(shí)態(tài)。

（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.

[點(diǎn)撥]1. will表示請(qǐng)求或建議，常和第二人稱連用，would更委婉。will和would還可以表示說話人的意愿和決心，常和第一及第三人稱連用，would表示過去。will和would表示習(xí)慣性動(dòng)作或某種傾向，would為過去時(shí)態(tài)，常譯成“總是”。如：Fish will die without water. My grandpa would talk to us for hours if you give him the chance.

2. shall用于第一人稱或第三人稱的疑問句，表示征詢對(duì)方意見。shall用于第二、三人稱，表示說話人給對(duì)方的許諾、命令、警告、威脅。shall用于第三人稱的條約、規(guī)章、法令等文件中，表示義務(wù)，意為“應(yīng)該”。

3. should和ought to表示義務(wù)，意為“應(yīng)該”，ought to比should語氣更強(qiáng)烈。

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

（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？

[點(diǎn)撥]1. need表示“需要”，作為情態(tài)動(dòng)詞只用于否定句或疑問句。對(duì)于need疑問句的肯定答復(fù)和否定答復(fù)和must一樣，肯定答復(fù)用must，否定答復(fù)用neednt或dont have to。need作為實(shí)義動(dòng)詞，表示需要，可用于任何句型中，后面可以接名詞、代詞、不定式或動(dòng)名詞。

2. “neednt have done”表示“本不需要做某事卻做了”，是一種虛擬語氣的表達(dá)。

3. dare表示“敢”，作為情態(tài)動(dòng)詞，通常用于否定句、疑問句或條件從句中;作為實(shí)義動(dòng)詞，在肯定句中要接to，在否定句或疑問句中可省略to。