成人高考高起点英语语法归纳：情态动词二

 情态动词(二)

　　内 容 提 要

　　情态动词有can(能)，may(可以)，must(必须)，have to(不得不)，ought to(应该)，dare(敢)，used to(过去经常)，had better(最好)，would rather(宁愿)。在肯定句中它们后边都要接 动词原形 .在否定句中，can，may，must和dare后边加not;have to和ought to分别在have和ought后加not;used to的否定式可用used not to，也可用didn't use to，但后者用得较多;had better和would rather的否定式分别是had better not和would rather not.这些情态动词与现在完成时连用在某种意义上有一定的虚拟性。

　　情态动词与完成时的使用

　　一、must+have+ED分词：用于肯定句，表示对过去情况的一种肯定推测，表示"肯定，一定"

　　1) It around nine o'clock when I drove back home because it was already dark.

　　[A] had to be [B] must have been [C] was to be [D] must be

　　2) John's score on the test is the highest in the class;

　　[A] he should study last night

　　[B] he should have studied last night

　　[C] he must have studied last night

　　[D] he must had to study last night

　　3) After searching [A] for evidence in the house，the police concluded [B] that the thief must have come in [C] through the window and stole [D] the silver while the family was asleep.

　　二、may (might)+have+ED分词：用于肯定句和否定句，表示对已发生事情的不肯定的推测，相当于"可能，大概，"其中might较may 语气更弱，把握更小

　　She might have gone to see her doctor last week， but I am not sure.

　　上星期或许她去看医生了，但我不敢肯定。

　　Don't worry， your husband may not have been hurt seriously.

　　别急，你丈夫也许伤得不厉害。

　　三、should(ought to)+have+ED分词：肯定句表示过去本应发生的事却没有发生;否定句表示已发生了本不该发生的事。前者可译为"本应，"后者为"本不该"

　　You should have apologized to her for not soon replying to the letter. 你本应向她道歉，说明为什么没能及时回信。(可你没这么做)

　　4) You yesterday if you were really serious about your work.

　　[A] ought to come[B] ought to be coming[C] ought to have come[D] ought have come

　　四、can(not) +have+ED分词

　　He is an hour late -- He can have been delayed by fog. Of course，that's a possibility.他迟到了1小时，可能因为大雾而耽搁了。当然这只是可能性问题。

　　The poem can not have been written by her since she was only five years old then.这诗不可能是她写的，因为她那时才5岁。

　　五、"could+have+ED分词"有时用于表示过去的时间，说明某事可能或不可能已发生;有时可表示过去本来可以做某事，但却未做

　　I simply can't understand how he could have made such a mistake. 我简直不明白他怎么会犯那样的错误。

　　He walked there，but he could have taken a taxi. 他走着去了，可当时完全可以坐出租。

　　"couldn't+have+ED分词"还表示无论如何也不可能或没有做到

　　I couldn't have called you. I wasn't near a telephone. 反正我也不可能给你打电话，我附近没有电话。

　　5) "We didn't see him at the lecture yesterday.""He it."

　　[A] mustn't attended[B] couldn't have attended[C] would have not attended[D] needn't have attended

　　六、needn't+have+ED分词：表示对过去不必做的事情却做了，可译为"其实不必"

　　6) You all these parcels yourself.The shop would have delivered them if you had asked a shop assistant.

　　[A] didn't need to carry[B] needn't have carried[C] needn't carry[D] didn't need carry

　　七、used to 表示过去的习惯动作或状态，现在已不存在，在否定陈述句中，一般用didn't use to，也可用used not to;在疑问句中用"Did…use to"。used to还可never，often，always等连用。注意used to与be used to的不同，后者表示be accustomed to "习惯于某种状态"，而且跟接名词或ING形式，而used to后接动词原形，试比较

　　He used to drink. 表示"他过去经常喝酒"而现在不喝了。

　　He is used to wine (He is used to drinking wine) at each meal.

　　表示"他现在已养成习惯，每顿饭喝点葡萄酒。"

　　八、had better表示"最好……"，后接动词原形，其否定式为had better not+动词原形

　　You had better not follow his behavior. 你最好不要学他。

　　九、would rather 意思是"宁愿"，表示选择。它有两种用法，一是在肯定句中后边直接跟动词原形，其否定句是在would rather 后加not，即 would rather not+动词原形;二是它后边可以跟接从句，该从句的谓语动词用一般过去式表示虚拟语气。由于would rather表示选择，它后边可跟接than She would rather sleep than talk rubbish. 她宁愿睡不愿闲聊。

　　7) "Did you criticize him for his mistakes?"--"Yes，but it."

　　[A] I'd rather not do[B] I'd rather not doing[C] I'd rather not have done[D] I'd rather not did

　　[注] would rather和had rather都表示"宁愿"，在用法上也没有区别。但如果说would rather与had rather完全一样(Longman Dictionary of Comtemporary English 如是说)，这一说法有争议。其实had rather在现代标准英语中几乎已经不用了。这对我们考试来说是比较重要的，因为一般考题作为标准英语是不用had rather的。

　　十、例题解析

　　1) B为正确答案。2) C为正确答案。

　　3) D错。改为stolen.这里C处和D处是并列的谓语，D处相当于must have stolen.

　　4) C为正确答案。5) B为正确答案。6) B为正确答案。7) C为正确答案。