考點一 can,could與be able to的用法
規則1表示現在的能力用can,am/is/are able to;表示將來的能力用will be able to。
However great the difficulties may be, we can overcome them.
哪怕是再大的困難我們也能克服。
規則2表示過去的能力用could(不表示是否成功地做了);was/were able to表示過去有能力做而且成功地做了。
The fire spread through the building very quickly, but everyone was able to get out.
儘管這場大火迅速蔓延了整個大樓,但是每個人都逃了出去。
規則3 can/could表示禮貌地請求別人做某事,意為“能,可以”。
Could/Can I borrow your reference books?
我可以借你的參考書嗎?
規則4 固定表達:cannot(can't)…too/over/enough表示“無論怎麼……也不(過分)”,用來加強語氣。cannot/couldn't but do sth不得不/只好做某事。
①You cannot be too careful. 你要特別小心。
②I couldn't but choose to wait. 我只好選擇等待。
考點二 may與might的用法
規則1 表示請求、允許時,might比may的語氣更委婉一些,否定回答時要用mustn't,表示“不可以”“禁止”“阻止”之意。
規則2 may/might還可以表示推測,意為“可能”。
He may be very busy these days. 他這些天可能很忙。
規則3 “may/might as well+動詞原形”意為“最好,倒不如”。
If you think the price of beef is too high,you might as well buy some pork.It depends on you.
如果你認為牛肉太貴的話,你不妨買些豬肉。你自己決定。
考點三 must/have to的用法
規則1 表示“必須;應該”,must一般指主觀,而have to指客觀,表示“不得不”。
①We must do everything step by step.
我們必須循序漸進地做每件事。
②I have to go now for I've a meeting 15 minutes later.
我現在必須走了,因為15分鐘後我有個會。
規則2 mustn't表禁止,而have to的否定式意為“不必”。
①Smoking mustn't be allowed in the office.
辦公室裡不許吸菸。
②—Must we hand in our exercise today?
—No, you don't have to.
“我們今天必須交作業嗎?”
“不,不必今天交。”
規則3must表示推測意為“一定會”,此時不能用於否定句。
He must be ill. He looks so pale.
他一定病了,他的臉色蒼白。
考點四 will, would/used to的用法
規則1 用於各種人稱,表示意志或決心。will指現在,would則指過去。
I will do my best to help you in every way.
我會盡最大的努力在各方面幫助你。
規則2 用於第二人稱的疑問句中表示禮貌地詢問和請求,would 比 will更委婉。
Would you teach us how to drive a car?
你願意教我們如何開車嗎?
規則3 表示習慣性、經常性、傾向性,意為“總是,慣於”。 will指現在,would指過去。
He would come to see me on Sunday when he was in Beijing.
當他在北京的時候經常在星期天來看我。
規則4 表示功能,意為“能”或“行”。
He tried to open the door again, but it wouldn't open.
他再次試著開門,但就是打不開。
規則5 would 與used to
used to表示過去經常性或習慣性的動作或狀態,現在已經結束,would則表示有可能再發生。
①People used to believe that the earth was flat.
過去,人們總以為地球是扁平的。(現在已不再這樣認為)
②He would go to the park as soon as he was free.
過去,他一有空就去公園。(現在有可能還去)
考點五 shall/should/ought to的用法
規則1 shall表示徵詢意見,用於第一、第三人稱疑問句。
Shall I get you some tea?我給你弄一些茶好嗎?
規則2 shall表示說話人的意願,有命令、允諾、警告、決心等意思,用於第二、第三人稱。
You shall do as I say.你應該按我說的做。(命令)
規則3 shall用在條約、規章、法令等文件中,表示必然結果,多用於第二、三人稱,常意為“必須”。
According to the newly-made traffic regulation,whoever drives through a red light shall be fined 200 yuan.
根據新的交通法規,不論誰駕車闖紅燈,罰款200元。
規則4 should表示推測或責備,意為“想必一定,照說應該,估計”等;表推測時往往指推測有一定的依據。
The film should be very good as it is starring first-class actors.
這部電影是一流演員主演的,估計拍得很好。
規則5 should用於表示驚奇、遺憾不該發生的事情,常意為“竟然”。
Why should you be so late today?
為什麼你今天竟然這麼晚?
考點六 need與dare的用法
規則1 need作情態動詞表示“需要,必要”。通常用於否定句、疑問句、條件句中,且只有現在時,其他時態用have to的相應形式代替。
①You needn't water the tomato plants now.
現在你不需要為番茄植株澆水。
②—Need he come now?
—Yes, he must./No, he needn't./No, he doesn't have to.
“他現在需要來嗎?”
“是的,他必須來。/不,他不必來。/不,他不必來。”
規則2 dare作情態動詞表示“敢於”,用於否定句、疑問句和條件句中。
①She dare not go there.她不敢去那兒。
②How dare he do such a thing?他怎麼敢做這樣一件事?
[溫馨提示] dare和need還可以用作行為動詞,其變化與一般動詞相同。
①The girl didn't dare (to) go home.這個女孩不敢回家。
②Do you dare to jump into the ocean?你敢跳進海里嗎?
考點七 情態動詞表推測的用法
規則1can用於肯定句中表示客觀的可能性,意為“有時會”;用於疑問句中可以表示推測,意為“可能”,有時表示一種驚訝的語氣;用於否定句中也可以表示推測,can't意為“不可能”,語氣很強烈。
You'd better put on a heavy coat.Sometimes it can be very cold here at night.
你最好穿上一件厚的大衣,在這裡晚上有時很冷。
規則2may/might用於肯定句中可以用來表示不十分肯定的推測,意為“有可能”;用於否定句中也可以表示推測,may not意為“可能不”,表示一種不太確定的語氣。
He has a car. He may come by car, but I am not sure.
他有輛車,他可能開車來,但我不確定。
規則3 must表示推測時只能用於肯定句中,意為“一定,必定”,表示十分肯定的語氣(在疑問句中或否定句中要用can/could)。
She can't be a Danish. She must be a Norwegian.
她不可能是丹麥人。她一定是挪威人。
規則4 should用來表示推測時意為“應該”,即含有“按道理來說應當如此”的意思。
There shouldn't be any difficulty about passing the road test since you have practised a lot in the driving school.
因為你在駕校練習了那麼多,通過路考應該沒什麼困難。
考點八 “情態動詞+have done”的用法
must have done 一定做過,其否定形式為can't/couldn't have done
can/could have done(虛擬)本來能夠做卻未做；(對過去的推測)可能做過
can't/couldn't have done(對過去的推測)不可能做過
may/might have done(對過去的推測)或許/可能做過
should/ought to have done(虛擬)本該做卻未做,其否定形式表示本不該做卻做了
needn't have done(虛擬)做了本沒有必要做的事情
①Sorry,I'm late.I might have turned off the alarm clock and gone back to sleep again.
對不起,我遲到了。我可能把鬧鐘關掉後又睡著了。
②Look!There are so many mistakes in your composition.You should have fixed full attention on it.
看!你的作文裡有這麼多的錯誤。你本應該把所有的注意力都集中在它上面的。
考點九 虛擬語氣
規則1if虛擬條件句的使用規則
與現在事實相反：動詞的過去式(be用were)；should/would/could/might+動詞原形
與過去事實相反：had+過去分詞；should/would/could/might+have+過去分詞
與將來事實相反：should/were to+動詞原形;動詞的過去式；should/would/could/might+動詞原形
①If I had done it in time, I should have had a good time.
如果我及時做的話,日子就好過多了。(可惜當時沒能及時做)
②If it were to rain tomorrow, I should not drive my car.
如果明天下雨的話,我就不開車了。(明天的情況還不知道)
[溫馨提示] ①在條件句中,如果有were, had, should等,則可省略if,但應注意把were, had, should等提到從句主語之前。
If he were to come, I would join him in the discussion. =Were he to come, I would join him in the discussion.
如果他來,我將和他一道參加討論。
②有些虛擬條件句沒有從句,虛擬條件句是通過上下文或介詞短語表示出來的。
But for air and water, there would be no life on the earth. 要是沒有空氣和水,地球上就沒有生命。(介詞短語but for提供了虛擬條件)
Without your help, we might not finish the task earlier. 要是沒有你的幫助,我們可能不會提早完成任務。(介詞短語without your help相當於虛擬條件句)
規則2 (should+)do…結構的虛擬語氣
(1)用於表示建議、願望、命令等動詞後的賓語從句中常見的動詞有:demand,order,require,insist,suggest,propose,advise,request,urge,command,prefer,desire,recommend等。賓語從句中的虛擬語氣結構為“should+動詞原形”,should可以省略。
The school recommends parents (should)not permit their children to swim in rivers or lakes during summer holidays.
學校建議父母在暑假不要允許他們的小孩在河裡或湖裡游泳。
(2)用於主語從句中
在“It is desired/suggested/proposed/recommended/necessary/important/strange/natural/a pity/essential+that從句”中,從句的謂語動詞用“should+動詞原形”,should可以省略。
It is suggested that the meeting (should) be put off till next week because of the bad weather.
由於壞天氣,人們建議會議推遲到下週。
(3)用於表語從句和同位語從句中
在suggestion,proposal,order,plan,idea,request,advice等名詞後的表語從句和同位語從句中要用虛擬語氣,其構成是“should+動詞原形”,should可以省略。
Your suggestion that the door (should)be shut when we leave is reasonable.
你的那個當我們離開的時候應該關上門的建議是合理的。
規則3 其他句型中的虛擬語氣
(1)would rather/wish後的賓語從句中,表示願望,意為“寧願;但願”。用一般過去時表示與現在或將來事實相反;用過去完成時表示與過去事實相反。
When my father is upset,he would rather we left him alone.
當我的父親煩惱的時候,他更喜歡我們不打擾他。
(2)在“It is (about/high)time+that從句”中,謂語動詞常用過去式或“should+動詞原形”表示虛擬語氣。
It's high time that we devoted ourselves to environmental protection and ecological improvement.
是我們致力於環境保護和生態改善的時候了。
(3)as if,as though引導的表語從句和方式狀語從句中常用虛擬語氣,與現在事實相反用一般過去時;與過去事實相反用過去完成時。
She speaks English as if/as though she were a native of New York.
她講起英語來好像她是一位地道的紐約人。
(4)if only引導的感嘆句中,用虛擬語氣表示願望。
Look at the trouble we're in.If only we had taken our teacher's advice!
看看我們所處的困境,要是我們接受老師的建議就好了!
誤區之一 情態動詞基本用法的誤用
【誤】 I won't thank you too much for all your help to my son while we were away from home.
【正】 I can't thank you too much for all your help to my son while we were away from home.
[分析] won't改為 can't。固定句型can't/couldn't…too…意為“再……都不為過”。
誤區之二 情態動詞表示“推測”語氣的誤用
【誤】 I didn't see Mary at the meeting yesterday. She must have been ill, I guess.
【正】 I didn't see Mary at the meeting yesterday. She might have been ill, I guess.
[分析] must改為might。考查情態動詞表示推測語氣的運用。根據“…I guess.”可知,這是一種不太有把握的猜測,而且又是肯定句,因此must改為might。must表示推測意義時,語氣較強,較肯定;can/could多用於否定或疑問句中。
誤區之三 “情態動詞+have done” 表示“虛擬”語氣的誤用
【誤】 The plant is dead. Maybe I should give more water.
【正】 The plant is dead. Maybe I should have given more water.
[分析] give改為have given。根據第一句可知,植物已經死亡,所以應該是自責,故用should have done表示“本應該做……而未做”。
誤區之四 條件狀語從句中的虛擬語氣的誤用
【誤】 Sorry, I am too busy now. If I have time, I would certainly go for an outing with you.
【正】 Sorry, I am too busy now. If I had time, I would certainly go for an outing with you.
[分析] have改為had。分析語境可知,從句是對現在情況的假設,故謂語的時態為一般過去時。
誤區之五 賓語從句中的虛擬語氣的誤用
【誤】 I'd rather I have a room of my own, however small it is.
【正】 I'd rather I had a room of my own, however small it is.
[分析] have 改為had。would rather後接賓語從句時,從句要用虛擬語氣。根據語境可知此句是對現在情況的假設,故謂語用一般過去時。
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