六级语法详解：情态动词（二）

　　情态动词有can(能),may(能够),must(必须),have to(不得不),ought to(应该),dare(敢),used to(从前经常),had better(最好),would rather(情愿)。在肯定句中它们后边都要接 动词本相 。在否认句中，can,may,must和dare后边加not；have to和ought to辨别在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。这些情态动词与当初实现时连用在某种意思上有必定的虚构性。 情态动词的六级语法详解：

　　情态动词与实现时的利用

　　一、must+have+?ED分词：用于肯定句，表现对过去情况的一种肯定揣摩，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 www,英语培训. .com

　　［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揣测，相称于"可能，大略，"其中might较may 语气更弱，控制更小

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

　　上星期或者她去看医生了，但我不敢确定。

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

　　别急，你丈夫兴许伤得不厉害。

　　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"的六级语法知识点。

　　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，可能因为大雾而延误了。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产生；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，可当时完全可能坐出租。

　　"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，我附近不电话。

　　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件却做了，可译为"实在不用"

　　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，畸形用didn't use to，也可用used not to；在疑难句中用"Did…use to"。used to还可never,often,always等连用。留心used to与be used to的不同，后者表示be accustomed to "习惯于某种状况"，而且跟接名词或?ING形式，而used to后接动词原形，试比较下面两个六级语法例句的区别：

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

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

　　表示"他当初已养成习惯，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"，表示决定。它有两种用法，一是在断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从前式表示虚构语气。由于would rather表示取舍，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跟had rather都表示"甘心"，在用法上也不差异。但如果说would rather与had rather完整一样(Longman Dictionary of Comtemporary English 如是说)，这一说法有争议。切实had rather在古代标准英语中几乎已经不用了。这对咱们考试来说是比较重要的，因为个别考题作为尺度英语是不必had rather的。

　　十、六级语法例题解析

　　1) B为准确答案。2) C为正确谜底。

　　3) D错。改为stolen。这里C处跟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。