英語語法詳解 情態(tài)動詞（二）

　　情態(tài)動詞有can(能),may(可以),must(必須),have to(不得不),ought to(應該),dare(敢),used to(過去經(jīng)常),had better(最好),would rather(寧愿)。在肯定句中它們后邊都要接 動詞原形 。在否定句中，can,may,must和dare后邊加not；have to和ought to分別在have和ought后加not；used to的否定式可用used not to，也可用didn't use to，但后者用得較多；had better和would rather的否定式分別是had better not和would rather not。這些情態(tài)動詞與現(xiàn)在完成時連用在某種意義上有一定的虛擬性。

　　情態(tài)動詞與完成時的使用

　　一、must+have+?ED分詞：用于肯定句，表示對過去情況的一種肯定推測，表示"肯定，一定"

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

　�。跘］ 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;

　�。跘］ he should study last night

　�。跙］ he should have studied last night

　　［C］ he must have studied last night

　�。跠］ 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分詞：用于肯定句和否定句，表示對已發(fā)生事情的不肯定的推測，相當于"可能，大概，"其中might較may 語氣更弱，把握更小

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

　　上星期或許她去看醫(yī)生了，但我不敢肯定。

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

　　別急，你丈夫也許傷得不厲害。

　　三、should(ought to)+have+?ED分詞：肯定句表示過去本應發(fā)生的事卻沒有發(fā)生；否定句表示已發(fā)生了本不該發(fā)生的事。前者可譯為"本應，"后者為"本不該"

　　You should have apologized to her for not soon replying to the letter. 你本應向她道歉，說明為什么沒能及時回信。(可你沒這么做)

　　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分詞

　　He is an hour late -- He can have been delayed by fog. Of course,that's a possibility.他遲到了1小時，可能因為大霧而耽擱了。當然這只是可能性問題。

　　The poem can not have been written by her since she was only five years old then.這詩不可能是她寫的，因為她那時才5歲。

　　五、"could+have+?ED分詞"有時用于表示過去的時間，說明某事可能或不可能已發(fā)生；有時可表示過去本來可以做某事，但卻未做

　　I simply can't understand how he could have made such a mistake. 我簡直不明白他怎么會犯那樣的錯誤。

　　He walked there,but he could have taken a taxi. 他走著去了，可當時完全可以坐出租。

　　"couldn't+have+?ED分詞"還表示無論如何也不可能或沒有做到

　　I couldn't have called you. I wasn't near a telephone. 反正我也不可能給你打電話，我附近沒有電話。

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

　�。跘］ mustn't attended［B］ couldn't have attended［C］ would have not attended［D］ needn't have attended

　　六、needn't+have+?ED分詞：表示對過去不必做的事情卻做了，可譯為"其實不必"

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

　�。跘］ didn't need to carry［B］ needn't have carried［C］ needn't carry［D］ didn't need carry

　　七、used to 表示過去的習慣動作或狀態(tài)，現(xiàn)在已不存在，在否定陳述句中，一般用didn't use to，也可用used not to；在疑問句中用"Did…use to"。used to還可never,often,always等連用。注意used to與be used to的不同，后者表示be accustomed to "習慣于某種狀態(tài)"，而且跟接名詞或?ING形式，而used to后接動詞原形，試比較

　　He used to drink. 表示"他過去經(jīng)常喝酒"而現(xiàn)在不喝了。

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

　　表示"他現(xiàn)在已養(yǎng)成習慣，每頓飯喝點葡萄酒。"

　　八、had better表示"最好……"，后接動詞原形，其否定式為had better not＋動詞原形

　　You had better not follow his behavior. 你最好不要學他。

　　九、would rather 意思是"寧愿"，表示選擇。它有兩種用法，一是在肯定句中后邊直接跟動詞原形，其否定句是在would rather 后加not,即 would rather not＋動詞原形；二是它后邊可以跟接從句，該從句的謂語動詞用一般過去式表示虛擬語氣。由于would rather表示選擇，它后邊可跟接than

　　She would rather sleep than talk rubbish. 她寧愿睡不愿閑聊。

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

　�。跘］ I'd rather not do［B］ I'd rather not doing［C］ I'd rather not have done［D］ I'd rather not did

　�。圩ⅲ� would rather和had rather都表示"寧愿"，在用法上也沒有區(qū)別。但如果說would rather與had rather完全一樣(Longman Dictionary of Comtemporary English 如是說)，這一說法有爭議。其實had rather在現(xiàn)代標準英語中幾乎已經(jīng)不用了。這對我們考試來說是比較重要的，因為一般考題作為標準英語是不用had rather的。

　　十、例題解析

　　1) B為正確答案。2) C為正確答案。

　　3) D錯。改為stolen。這里C處和D處是并列的謂語，D處相當于must have stolen。

　　4) C為正確答案。5) B為正確答案。6) B為正確答案。7) C為正確答案。