《情态动词和虚拟语气专题》由会员分享，可在线阅读，更多相关《情态动词和虚拟语气专题（6页珍藏版）》请在金锄头文库上搜索。
1、情态动词和虚拟语气专题情态动词的类型和特征:1. 情态动词的类型(1)只作情态动词的有:must,can (could),may(might),ought to ;(2)可作情态动词也可作实义动词的有:need ,dare (美语中常用作实义动词)(3)可作情态动词也可作助动词的有: shall (should),will (would);(4)具有情态动词的某些特征的有:have (had) to ,used to .二.情态动词的特征:1.有一定的词义,但不能单独做谓语,它们要和行为动词或连系动词连用,构成谓语.2.适用于主语的各种人称和数(have to 例外,主语是第三人称单数时,要用
2、has to ).如:we /He must work hard .I have to walk home . He has to walk home .3.后面接动词原形,即不带to 的不定式(ought to ,have to ,used to 本身带有to).如:He maylose his way . You ought ot obey the law .4.具有助动词的作用,即可用来构成否定句,疑问句及用于简明答语.如: -I cant swim .(an you swim ? ) -No ,I cant either.二.情态动词用法要点: (一) 表能力:1.表示现在的或一般的能
3、力:表现在的或一般的能力用can或be able to ,一般的能力即你无论什么时候想做就能做到的能力.表示现在的或一般的能力时,can tebe able to 更普遍.如:A computer cant think for itself ;it must be told what to do (一般能力) He is a native speaker of English ,so he can of course speak English quite well (一般能力) I am starving(挨饿) to death . I can eat two bowls of rice
4、now .(现在的能力)2.表示将来的能力:表示将来的能力用will be able to .如:If you have a good sleep ,you will be able to work out this problem .3. 表示过去的能力 (1) could ,was/were able to 表示过去一般的能力,但不表示做或未做某事;(2)was /were able to 表示过去有能力,并且成功地做了某事,相当于managed to do something /succeeded in doing something;(3)“could have +过去分词”表示过去有
5、能力做,但未做.如:She could /was able to sing like an anged when she was a child (过去一般的能力) I could have worked out the problem ,but I didnt (过去有能力做但未做)训练题: 1.I should have been there ,but I not find the time .A.would B.could C.might D.should2. I stayed at a hotel while in New York . Oh ,did you ? You with B
6、arbara .A.could have stayed B.could stay C.would dtay D.must have stayed3. The fire spread through the hotel very quickly but everyone get out .A.had to B.would C.could D.was able to二.表推测(可能性)1.可能性可分为客观的可能性,和具体事情实际发生的可能性两种,所谓客观的(理论的)可能性,即不涉及具体某事是否会发生,此种用法常常可以说明人或事物的特征.情态动词can 可用于肯定句中表示客观的(理论的)可能性,而表
7、示具体事情实际发生的可能性时, can一般不用于肯定句.如:Accidents can happen on such rainy days .这样的多雨天可能会发生事故.(客观的可能性).2.表示具体事情实际发生的可能性: (1)表示具体事情实际发生的可能性的层次比较(见下表):词形肯定式否定式疑问式must必定,必然/Will很可能,大概不会,不该会.吗?Would可能性比will小语气比wont弱语气比will弱Should说话者有较大的试探性结果/Ought to说话者有较大的试探性(含义同should)/Can/不可能有可能吗?Could微弱的可能性不可能语气比can弱May或许,也许
8、,也未可知,也说不定可能不/might比may还弱比may not还弱/(2)表示具体事情实际发生的可能性时,may ,must 常用于肯定句,一般不用于否定句,疑问句(may not 表示“可能不”),can 常用于否定句,疑问句或感叹句中,表示疑惑,惊讶或不相信等意思;could 既可用于肯定句又可用于否定句，疑问句中。如：This cant /couldnt be done by him (这不可能是他干的。) （表不相信）This may not be done by him . 这不可能不是他干的。（表不确定）He could be on his way home now . 他现在
9、可能在回家的路上了。（could 不如may /might常用 ） （an this be done by him? ）这可能是他干的吗？ （表示疑惑，惊讶）Mr Bush is on time for everyghing .How can it be that he was late for the opening ceremony ? （表示疑惑，惊讶）I didnt hear the phone . I must have been asleep .(表肯定)-Are you coming to Jeffs party ? -Im not sure .I might go to the
10、 concert instead .(表示不确定)。训练题：用can,could,may ,might ,must 填空:4.Is Johu coming by train ? -He should ,but he not .He likes driving his car .5.Peter come with us tonight ,but he isnt sure yet .6. Sorry Im late , I have turned off the alarm clock and gone back to sleep again .7.That not be Mary . Shes
11、in hospital .8. How you be so stupid?(3).Would ,could ,should ,might 并不一定与过去时间有关，而表示可能性，弱于它们相应的表现形式。如：This may /might be done by him .这件事可能是他干的。（证据依次递减）（4）should 表推测时，表示确定或可能有的未来或期望，即合乎理想的情况或结果。如：He should be around sixty years old .他可能60岁上下。（表确定）He ought toe home by now .他现在该到家了。（表确定或期待）Its nearly
12、seven oclock .Jack should be here at any moment (表确定或期待).-When can I come for the photos ? I need them tomorrow afternoon?They should be ready by 12:00(表期待)。三表示 请求，允许，允诺。1.当对方是决策者时，你代表你（们）自己（I ,we）,或代表第三者（he ,she ,they）向对方（you）请求或提出建议时用，（1）Shall/May (Might)/can (could )/I /we ?(2) Shall he /she /the
13、y ?(3)Would /will you ?如Shall we begin our class ?shall the driver wait outside ?When shall my father be able to leave hospital?Can/could I leave now ?Would you do me a favor ?1. could/might /would /should 表委婉的功能。如-Could /might I use your bike tomorrow morning ?-Yes ,you can /may (否定：No ,Im afraid n
14、ot )不可说：Yes,you could /might . 回答允许时；用could /might 表委婉是不恰当的。如：- Could I borrow your dictionary ? Yes,of course ,you can .训练题：（9）-The room is so dirty . we clean it ? -of course .A.Will B.Shall C.Would D.Do(10) - he come to see you ? -of course ,please .And Id rather he told me the truth .A.Will B.Sh
15、all C.Would D.Do3.当你自己（I）是决策者时，给对方（you）或第三者（he ,she ,they ）以命令，警告，允诺或威胁时，要用shall.此外，当颁布法律，规定时，也要用shall.如：You shall get out at once ,and he also shall (=I order you and him to get out at once ) 你马上给我滚出去！他也一样。（说话者的意志）It has been announced that candidates shall remain in their seatw until all the papers have been collected .（规则或规定）在所有试卷收一来之前，应试者必须留在座位那里。训练题 ：（11）He asked kme for this book many times ,please
