2024屆高考英語一輪復(fù)習(xí)語法專練課件：9 情態(tài)動詞和虛擬語氣（牛津譯林版）
與過去事實(shí)相反的假 設(shè) If+主語+had+過去分 詞 主語+should/would/ could/might+have+過 去分詞 If you had taken my advice,you would not have failed in the ex-ams. 如果你早聽了我的建議,你考試就能通過了。 與將來事實(shí)相反的假 設(shè) 1.If+主語+動詞的過去式 2.If+主語+were to+動詞原形 3.If+主語+should+動詞原形 主語+should/would/ could/might+動詞原 形 If he should not come tomorrow,we should put off the meeting till next Monday. 如果明天他不來,我們就把會議推遲到下周一。 使用虛擬條件句時(shí)要注意以下幾點(diǎn): 1.當(dāng)條件狀語從句表示的行為和主句表示的行為所發(fā)生的時(shí)間不一致時(shí),被稱 為“錯綜時(shí)間條件句”,動詞的形式要根據(jù)它所表示的時(shí)間作出相應(yīng)的調(diào) 整。如: If you had followed my advice just now,you would be better now.如果你剛才聽 了我的建議,你現(xiàn)在就好多了。 If you had studied hard before,you would be a college student now.如果你以前努 力學(xué)習(xí)的話,你現(xiàn)在早就是大學(xué)生了。 2.if省略句 在虛擬條件句中可省略if,把were,had,should提到句首,變?yōu)榈寡b句式。如: If I were at school again,I would study harder. →Were I at school again,I would study harder. 如果我還有上學(xué)的機(jī)會,我會更加努力地學(xué)習(xí)。 If you had come earlier,you would have caught the bus. →Had you come earlier,you would have caught the bus. 如果你來得早些,你就能趕上公共汽車了。 If it should rain tomorrow,we would not go climbing. →Should it rain tomorrow,we would not go climbing. 如果明天下雨的話,我們就不去登山了。 注意:若省略的條件狀語從句中的謂語動詞是否定形式時(shí),不能用動詞的縮略 形式。如:我們可以說Were it not for the expense,I would go abroad now.但不能 說Weren't it for the expense,I would go abroad now. 3.含蓄條件句 有時(shí)為了表達(dá)的需要,在虛擬語氣中并不總是出現(xiàn)if引導(dǎo)的條件句,而是通過 其他手段來代替條件句。如: What would you do with a million dollars(=if you had a million dollars)? 如果你有100萬美元,你會做什么? Without your help,we couldn't have finished the work ahead of time. =But for your help,...=If it had not been for your help,...=Had it not been for your help,... 沒有你的幫助,我們不可能提前完成這項(xiàng)工作。 I was ill that day.Otherwise,I would have taken part in the sports meeting.(副詞) 我那天病了。否則,我就參加運(yùn)動會了。 He telephoned to inform me of your birthday,or I would have known nothing about it.(連詞) 他打電話通知了我你的生日,否則,我對此一點(diǎn)都不知道。 I should have given you more help,but I was too busy.(連詞) 我本應(yīng)該多幫幫你,但我(那時(shí))太忙了。 4.even if,even though 也可用于虛擬語氣,其形式與if從句在虛擬語氣中的形式 相同。 二、虛擬語氣在名詞性從句中的運(yùn)用 1.用于賓語從句中 (1)wish后面的賓語從句一般用虛擬語氣,表示一種不可能實(shí)現(xiàn)的愿望。其謂 語動詞構(gòu)成形式為: ? 如: I wish(that)I were a bird and could fly freely in the sky. 我希望我是一只小鳥,能在天空中自由飛翔。 I wish(that)I had met that film star yesterday. 我希望昨天見到那個(gè)影星了。 How I wish it weren't raining now! 我多希望現(xiàn)在沒下雨啊! 此外,If only+句子=How I wish+that從句。如: If only I were a flying bird!=How I wish I were a flying bird! 我要是一只飛鳥該多好啊! If only I had seen the film!=How I wish I had seen the film! 我要是看了那部電影多好啊! (2)用于表示建議、愿望、命令等動詞后的賓語從句中,常見的動詞有:de- mand,order,require,insist,suggest,propose,advise等。賓語從句中的虛擬語氣結(jié) 構(gòu)為“should+動詞原形”,should可以省略。如: He suggested that we(should)start off early the next day. 他建議我們第二天早點(diǎn)出發(fā)。 They insisted that the boy(should)go with them. 他們堅(jiān)決主張那個(gè)男孩子跟他們一起去。 (3)在would rather后的賓語從句中,也用虛擬語氣,其構(gòu)成為would rather sb.+動 詞過去式/had done(從句動作先發(fā)生)。如: I would rather they didn't hear of the news. 我寧愿他們沒聽到那個(gè)消息。 (4)當(dāng)suggest表示“暗示,表明”之意,insist表示“堅(jiān)持說”之意時(shí),suggest/in- sist后的賓語從句不使用虛擬語氣,應(yīng)使用陳述語氣。如: The smile on his face suggested that he was satisfied with our work.他臉上的微 笑表明他對我們的工作很滿意。 The man insisted that he had never stolen the money. 那個(gè)人堅(jiān)持說他沒有偷錢。 在“It is desired/suggested/proposed/recommended/necessary/important/strange/ natural/a pity/essential+that從句”結(jié)構(gòu)中,從句的謂語動詞用“should+動詞原 形”,should可以省略。如: It is suggested that the meeting(should)be put off till next week.人們建議會議推 遲到下周。 It is strange that he (should)have acted toward his parents like that.(從句謂語動 詞動作在主句謂語動詞動作之前發(fā)生時(shí),從句謂語要用“should have+過去分 詞”,should可以省略) 真奇怪他竟然那樣對他的父母。 注意:以上句式也可以用陳述語氣。如: It's a pity that you can't dance. 2.用于主語從句中 真遺憾你不會跳舞。 3.用于表語從句和同位語從句中 在suggestion,proposal,order,plan,idea,request,advice等名詞后的表語從句和同 位語從句中要用虛擬語氣,其構(gòu)成是“should+動詞原形”,should可以省略。 如: My idea is that we(should)think it over before accepting it. 我的意見是在接受它之前我們要仔細(xì)考慮。 We all agreed to his suggestion that we (should)go to Dalian for sightseeing.我們 都同意他讓我們?nèi)ゴ筮B旅游的建議。 如果as if/as though引導(dǎo)的從句謂語動詞與主句謂語動詞所表達(dá)的動作同時(shí)發(fā) 生,從句用一般過去時(shí);如果as if/as though引導(dǎo)的從句謂語動詞所表達(dá)的動作 先于主句謂語動詞所表達(dá)的動作,從句用過去完成時(shí);如果as if/as though引導(dǎo) 的從句謂語動詞所表達(dá)的動作后于主句謂語動詞所表達(dá)的動作,從句謂語動 詞用would+動詞原形。如: He looks as if he were an artist.(同時(shí)) 他看起來像個(gè)藝術(shù)家。 She speaks English so fluently as if she had studied English in America.(先于) 她講英語如此流利,好像她在美國學(xué)過英語。 He learns English so hard as if he would go to the U.S.A.(后于) 他如此努力地學(xué)英語,好像他要去美國。 易混點(diǎn)總結(jié) 一、as if/as though用在虛擬語氣中 二、虛擬語氣用于定語從句中 It is(high)time(that)...句型中,定語從句的謂語動詞用過去式,或用“should+動 詞原形”(其中should不能省略)。此句型意為“(現(xiàn)在)該……”,用來表示提 議。如: It is(high)time that you went to school. 你該去上學(xué)了。 It is(high)time that we should start out. 我們該出發(fā)了。 高頻考點(diǎn)一 情態(tài)動詞表能力
can/could一般表示主語本身所具有的能力,意為:能,會;而be able to一般表示通 過努力能做到某事。 典例1????(2024浙江,4)It was so noisy that we ????hear ourselves speak. ?答案 couldn't ?解析 句意:這里如此嘈雜以至于我們無法聽到自己說話。根據(jù)語境可知此 處表達(dá)過去的能力故用couldn't。 考點(diǎn)清單 ? 高頻考點(diǎn)二 情態(tài)動詞表推測 情態(tài)動詞表推測分為:對現(xiàn)在情況和過去情況的推測、對情況肯定的推測、 否定的推測以及可能性的推測。對現(xiàn)在情況的肯定推測就用must,否定推測 就用can't,可能性推測就用can/could,may/might。對過去情況的肯定推測就用 must have done,否定推測就用can't have done,可能性推測就用can/could/may/ might have done。做題時(shí)要判斷是哪一種推測,還要判斷出是對現(xiàn)在還是對過 去情況的推測。 典例2????(2024重慶,12)You ????be Carol.You haven't changed a bit after all these years. ?答案 must ?解析 句意:你一定是卡蘿爾,這么多年過去了你一點(diǎn)也沒變。根據(jù)語境可 知此處表示對現(xiàn)在情況的肯定推測,所以要用must(一定)。 ? 高頻考點(diǎn)三 情態(tài)動詞表請求、許諾、允許 1.向?qū)Ψ教岢龌蛘髑笠庖姇r(shí)一般要用比較委婉的語氣,常用的句式有:Shall I/ he/they...?Could I...?May I...? 2.情態(tài)動詞shall用于第二、三人稱表示說話者命令、警告、許諾的語氣。表 示按照規(guī)章制度、法律、條例規(guī)定應(yīng)該怎么做也要用shall。這是高考對shall 的考查熱點(diǎn)。 典例3????(2024北京,27)????I have a word with you?It won't take long. ?答案 Can/May ?解析 句意:我能和你說句話嗎?不會花很長時(shí)間的。本題考查情態(tài)動詞的 基本用法。can/may可以,表請求允許。 ? 高頻考點(diǎn)四 情態(tài)動詞表必要性 must語氣最強(qiáng)烈,表示說話者堅(jiān)決認(rèn)為必須做某事;need語氣要比must弱,表示 說話者認(rèn)為有必要做某事;should在表示該含義時(shí),表示在義務(wù)上應(yīng)該做某 事。should還表示“竟然會,(將來)萬一”。 典例4????(2024北京,29)—Can't you stay a little longer? —It's getting late.I really ????go now.My daughter is home alone. ?答案 must ?解析????句意:——難道你不能再多逗留一會兒嗎?——時(shí)間不早了。我現(xiàn)在 確實(shí)得走了。我的女兒獨(dú)自一人在家。根據(jù)對話內(nèi)容可知空格處表示“必要 性”,故用must。 ? 情態(tài)動詞+have done 意義 must have done 想必/準(zhǔn)是/一定做了 否定式為can't/couldn't have done could have done 本來能夠做 can/could have done 過去可能會做 cannot/could not have done 1.過去不可能做 2.過去沒能夠做 may/might have done 也許/或許已經(jīng)做了……,一般只用于肯定句或否定句中(在否定句中表示“可能不”),不用于疑問句。用might則表示語氣更加不肯定 高頻考點(diǎn)五 情態(tài)動詞+have done should/ought to have done 本該做而實(shí)際上未做 shouldn't/ought not to have done 本不該做而做了 needn't have done 本來不必做而做了 had better have done 要是當(dāng)時(shí)做了就好了,用于事后的遺憾,含輕微的責(zé)備,其否定式had better not have done表達(dá)相反的含義 would rather have done 寧愿當(dāng)時(shí)做了,其否定式would rather not have done表達(dá)相反的含義,兩者都表示“后悔”之意 would like/love to have done 過去愿意做但未做成 典例5????(2024天津,7)I ????have worried before I came to the new school,for my classmates here are very friendly to me. ?答案 needn't ?解析 句意:在進(jìn)入這所新學(xué)校之前我本沒必要擔(dān)心,因?yàn)檫@里的同學(xué)對我 很友好。根據(jù)語境可知此處表達(dá)“過去對某事?lián)倪^,但現(xiàn)在看來這種擔(dān)心 沒有必要”,應(yīng)該用needn't have done。 ? 高頻考點(diǎn)六 虛擬語氣
虛擬語氣是用來表示與現(xiàn)在或過去的實(shí)際情況相反的假設(shè),近年來主要是考 查上述兩點(diǎn),而對將來可能情況的假設(shè)已很少涉及。注意下列幾種情況: 1.表示與現(xiàn)在實(shí)際情況相反的假設(shè):條件從句謂語動詞應(yīng)該用一般過去時(shí)(be 動詞用were),主句謂語動詞要用should/might/would/could+動詞原形。 2.表示與過去實(shí)際情況相反的假設(shè):條件從句謂語動詞應(yīng)該用過去完成時(shí),主 句謂語動詞要用should/might/would/could have done。 3.用其他形式來代替條件從句,常見的有:without,otherwise,but for等。 4.一些特殊動詞后的that從句中謂語動詞要用(should+)動詞原形,常常考查把 should去掉的情況。與這些特殊動詞相關(guān)的名詞形式后的that引導(dǎo)的同位語 從句的謂語動詞也符合這一原則。 5.需要特別注意的幾個(gè)結(jié)構(gòu):wish句式,as if/though句式,would rather...,It's high time...等。 典例6????(2024北京,34)If I ????(see)it with my own eyes,I wouldn't have be- lieved it. ?答案 hadn't seen ?解析 句意:如果不是我親眼看到,我是不會相信的。由主句謂語“wouldn't
have believed”可知此處為與過去事實(shí)相反的假設(shè),故if從句謂語動詞應(yīng)為 hadn't seen。 ? 知識清單一 情態(tài)動詞的用法要點(diǎn) 一、表能力 ? 如: I am starving to death.I can eat two bowls of rice now.(現(xiàn)在的能力) 我快餓死了,現(xiàn)在我能吃兩碗米飯。 If you have a good sleep,you will be able to work out this problem.(將來的能力) 知識清單 如果你好好睡一覺,你將能夠解出這道題。 The fire spread through the hotel very quickly but everyone was able to get out. (過去有能力做并且成功地做了某事) 盡管這場大火迅速蔓延到了整個(gè)賓館,但是每個(gè)人都逃了出去。 I could have worked out the problem,but I was too nervous.(過去有能力做但未 做) 我本來可以解出這道題,但我太緊張了。 1.可能性可分為客觀的可能性和具體事情實(shí)際發(fā)生的可能性兩種。所謂客觀 的(理論的)可能性即并不涉及具體某事是否會發(fā)生,此種用法常常可以說明人 或事物的特征。情態(tài)動詞can可用于肯定句中表示客觀的(理論的)可能性,而 表示具體事情實(shí)際發(fā)生的可能性時(shí),can 一般不用于肯定句。如: Accidents can happen on such rainy days. 在這樣的多雨天里可能會發(fā)生事故。(客觀的可能性) We may go to the cinema tonight,but we are not sure yet. 今晚我們可能去看電影,但還沒確定。(實(shí)際可能性,不用can) 2.表示具體事情實(shí)際發(fā)生的可能性: (1)表示具體事情實(shí)際發(fā)生的可能性的層次比較(見下表) 二、表推測(可能性) 詞形 肯定式 否定式 疑問式 must 必定,必然 / / should 按說應(yīng)該 應(yīng)該不會 / ought to 按說應(yīng)該 應(yīng)該不會 / can / 不可能 有可能嗎? could 微弱的可能 不可能 語氣比 can弱 may 或許,也許,也未 可知,也說不定 可能不 / might 比may還弱 比may not 還弱 / (2)表示具體事情實(shí)際發(fā)生的可能性時(shí),may,must常用于肯定句,一般不用于否 定句和疑問句(may not表示“可能不”);can 常用于否定句、疑問句或感嘆句 中,表示疑惑、驚訝或不相信等意思;could既可用于肯定句又可用于否定句、 疑問句中。如: This can't/couldn't be done by him. 這不可能是他干的。(表不相信) This may not be done by him. 這可能不是他干的。(表不確定) He could be on his way home now. 他現(xiàn)在可能在回家的路上了。(could 不如may/might常用) Can this be done by him? 這可能是他干的嗎?(表示疑惑、驚訝) Mr.Bush is on time for everything.How can it be that he was late for the opening ceremony? 布什先生做一切事情都非常守時(shí)。開幕式他怎么可能會遲到呢?(表示疑惑、 驚訝) I didn't hear the phone.I must have been asleep. 我沒聽見電話鈴響。我一定是睡著了。(表肯定) —Are you coming to Jeff's party? —I'm not sure.I might go to the concert instead.(表不確定) ——你要來杰夫的聚會嗎? ——我不確定。我可能要去音樂會。 (3)could,might并不一定與過去的時(shí)間有關(guān),而表示可能性弱于它們相應(yīng)的現(xiàn) 在時(shí)形式。如: This may/might be done by him. 這件事有可能是他干的。(語氣依次遞減) (4)should表推測時(shí),表示確定或可能有的未來或期望,即合乎理想的情況或結(jié) 果。如: He ought to/should be here on time—he started early enough. 他(應(yīng))該按時(shí)到這里——他出發(fā)得夠早的了。 We should arrive before dark. 我們按說能在天黑前到達(dá)。 The roads should be less crowded today. 按說今天路上就不那么擁擠了。 三、表示請求、允許、允諾 1.當(dāng)對方是決策者時(shí),你代表你(們)自己(I,we),或代表第三者(he,she,they)向?qū)?方(you)請示或提出建議時(shí)用:①Shall/May(Might)/Can(Could)I/we...?②Shall he /she/they...?③Would/Will you...?如: Shall the driver wait outside? 司機(jī)在外邊等著可以嗎? When shall my father be able to leave hospital? 我父親什么時(shí)候可以出院? Would you do me a favor? 請幫我一下,好嗎? 2.could/might/would/should表委婉的語氣。如: —Could/Might I use your bike tomorrow morning? —Yes,you can/may.(否定:No,I'm afraid not.) ——明天早晨我用一下你的自行車,行嗎? ——行,你用吧。(否定:不,恐怕不行。) 不可以說:Yes,you could/might.回答允許時(shí),用could/might表委婉是不恰當(dāng)?shù)摹?3.shall與第二、三人稱連用,用于陳述句,表示說話者的命令、警告、威脅;當(dāng) 宣布法律規(guī)定時(shí),也用shall。 You shall leave the room at once,and he also shall.(=I order you and him to leave the room at once.) 你馬上離開這個(gè)房間,他也一樣。(說話者的命令) It has been announced that candidates shall remain in their seats until all the pa- pers have been collected. 據(jù)宣布,在所有試卷收上來之前,應(yīng)試者必須待在自己的座位上。(規(guī)則或規(guī) 定) 四、表示必要性 1.must 常用來表示必要性,意為“必須”,must do sth.(現(xiàn)在或?qū)?必須做某 事。 2.don't have to do sth./don't need to do sth./needn't do sth.(現(xiàn)在或?qū)?不必做 某事。 3.表示過去沒必要做某事時(shí),分為以下情況: (1)needn't have done sth.本來不必做而做了某事 (2)didn't have to do sth./didn't need to do sth./It was not necessary to do sth.(過 去)不必做(不強(qiáng)調(diào)是否做了)某事 You needn't have worked that late last night.It was harmful to your health. 你昨晚本不必工作到那么晚。那對你的身體沒好處。 —Did you work very late last night? —No,I didn't.I didn't need to work very late. ——你昨天晚上工作到很晚嗎? ——不是很晚。我沒必要工作到很晚。 4.should也可以表示必要性,意為“(義務(wù)上)應(yīng)該”。should表示必要性時(shí),在 語氣上比must(必須)弱。“should+動詞原形”表示現(xiàn)在或?qū)響?yīng)該做(的必 要性);“should+have+過去分詞”表示過去本該做(的必要性)。如: I should go and visit him this afternoon,but I wonder if I will be free. 今天下午我應(yīng)該去看望他,但我不知道我是否有空。(表示將來的必要性) You should have come to the conference yesterday.What was the reason for your absence? 你昨天本應(yīng)該參加那個(gè)會議。你缺席的原因是什么?(表示過去的必要性) 五、表示“寧愿做某事”時(shí),可使用下面這些句式: ? ? 高考中對這類用法的考查主要側(cè)重結(jié)構(gòu),因此要熟記其結(jié)構(gòu)。 情態(tài)動詞+have done 用法 例句 must have done 想必/準(zhǔn)是/一定做了否定式為:can't/couldn't+have done It must have rained last night,for the road is quite muddy.昨晚一定下雨了,因?yàn)槁泛苣酀簟?can/could have done 1.本來能夠做 2.過去可能會做 Can he have gone to his aunt's? 他有可能去他姨媽家了嗎? cannot/could not have done 1.過去不可能 2.過去沒能夠 He cannot have forgotten it. 他不可能忘了那件事。 六、“情態(tài)動詞+have done”用法一覽表 may/might have done 也許/或許已經(jīng)做……,一般只用于肯定句或否定句中(在否定句中表示“可能不”),不用于疑問句中。might則表示語氣更加不肯定。 It's too late.I think he may have gone to bed.太晚了,我想他或許已經(jīng)睡了。 He may not have finished the work.他也許還沒完成那項(xiàng)工。 should/ought to have done 本該做而實(shí)際上未做 You ought to have done this exercise more carefully.你本應(yīng)該更仔細(xì)地做這個(gè)練習(xí)。 should not/ought not to have done 本不該做而做了 You shouldn't have told her the truth. 你本不該告訴她真相。 needn't have done 本不必做而做了 You needn't have taken a taxi here,for it was very near to my house.你本來不必打車來這里 的,因?yàn)殡x我家很近。 had better have done 當(dāng)時(shí)最好做了(其否定式had better not have done表達(dá)相反 的含義) You had better not have scold- ed her. 要是那時(shí)你沒責(zé)罵她就好 了。 would rather have done 寧愿當(dāng)時(shí)做了(其否定式 would rather not have done表 達(dá)相反含義,兩者都有“后 悔”之意) I raised objections at the meet- ing,but now I would rather not have done that. 我在會上提出了反對意見,但 現(xiàn)在我寧愿沒那么做。 would like/love to have done sth. 過去愿意做但未做成 I would love to have gone to the party last night,but I had to work extra hours to finish a re- port. 昨晚我本來很想去參加聚會 的,但我得加班完成一個(gè)報(bào) 告。 七、情態(tài)動詞的其他用法要點(diǎn): 1.cannot but+do sth.表示“不得不,只好做某事”。如: I cannot but choose to go.我只好去。 2.may well和may as well結(jié)構(gòu)。 “may well+動詞原形”是一種常用結(jié)構(gòu),意為“完全能,很可能”,相當(dāng)于“be very likely to+動詞原形”。如: He may well be proud of his son. 他大可為他的兒子感到自豪。 Her appearance has changed so much that you may well not recognize her. 她的模樣變化太大,你很可能認(rèn)不出她了。 “may as well+動詞原形”意為“最好,不妨,倒不如”。如: You may as well do it at once.你最好馬上就做這件事。 We may as well stay where we are. 我們留在現(xiàn)在的地方倒也不錯。 3.cannot(或can never)與enough連用表示“再……也不為過”。(具體用法見 形容詞和副詞專題。) 4.may可以用于祈使句,表示祝愿。如: May we never forget each other.愿我們彼此永不相忘。 May you return in safety.愿你平安歸來。 5.“Why/How+should”結(jié)構(gòu)表示說話人對某事不能理解,感到意外、驚訝等, 意為“竟會”。如: Why should you be so late today?你今天怎么來得這么晚? How should I know?我怎么會知道?(意為:我不知道。) 6.must表示“偏要,硬要”。如: Must you make so much noise? 你非得弄出這么大聲響嗎? 7.may作“可以”講時(shí),其否定式常用“mustn't”表示“禁止”;must作“必 須”講時(shí),其否定式是“needn't”,表示“不必”。如: —May I use your car? —No,you mustn't. ——我能用用你的車嗎? ——不,一定不能。 (委婉的拒絕可用:Sorry,but I am using it now.或You'd better not.等) —Must I work out the problem tonight? —No,you needn't. ——我今晚必須做出這道題嗎? ——不,不必。 8.need和dare的用法 need和dare兩者既可用作情態(tài)動詞也可用作實(shí)義動詞。作實(shí)義動詞時(shí),有人稱 和數(shù)的變化,可用于肯定句、否定句或疑問句中,構(gòu)成否定句或疑問句時(shí)要用 助動詞do,does,did;作情態(tài)動詞時(shí),沒有人稱和數(shù)的變化(dare的過去式為dared), 直接接動詞原形,多用于否定句和疑問句中,構(gòu)成否定句和疑問句時(shí)不用助動 詞。 另外,dare作情態(tài)動詞時(shí),還可用于條件狀語從句中,過去式為dared;作實(shí)義動詞 時(shí),dare用于疑問句或否定句,后面的to也可省略;I dare say是習(xí)慣說法,意為 “我想,大概”。如: He needn't do it.(情態(tài)動詞) He doesn't need to do it.(實(shí)義動詞) 他不必做這件事。 I didn't know whether he dared say that to him.(情態(tài)動詞,有時(shí)態(tài)變化) 我不知道他是否敢對他說那件事。 He didn't dare(to)do it.(實(shí)義動詞) He dared not do it.(情態(tài)動詞) 他不敢做這件事。 注意:need作實(shí)義動詞時(shí),還可表示“需要”,后接動名詞的主動形式表示 被動含義(詳見非謂語動詞專題)。如: The floor needs sweeping. 這地需要打掃了。 知識清單二 虛擬語氣 一、虛擬語氣在非真實(shí)條件句中的運(yùn)用
從句 主句 例句 與現(xiàn)在事實(shí)相反的假 設(shè) If+主語+動詞的過去 式(be動詞用were) 主語+should/would/ could/might+動詞原 形 If I were you,I should seize the chance to go abroad. 如果我是你,我就抓住 這次出國的機(jī)會。
與過去事實(shí)相反的假 設(shè) If+主語+had+過去分 詞 主語+should/would/ could/might+have+過 去分詞 If you had taken my advice,you would not have failed in the ex-ams. 如果你早聽了我的建議,你考試就能通過了。 與將來事實(shí)相反的假 設(shè) 1.If+主語+動詞的過去式 2.If+主語+were to+動詞原形 3.If+主語+should+動詞原形 主語+should/would/ could/might+動詞原 形 If he should not come tomorrow,we should put off the meeting till next Monday. 如果明天他不來,我們就把會議推遲到下周一。 使用虛擬條件句時(shí)要注意以下幾點(diǎn): 1.當(dāng)條件狀語從句表示的行為和主句表示的行為所發(fā)生的時(shí)間不一致時(shí),被稱 為“錯綜時(shí)間條件句”,動詞的形式要根據(jù)它所表示的時(shí)間作出相應(yīng)的調(diào) 整。如: If you had followed my advice just now,you would be better now.如果你剛才聽 了我的建議,你現(xiàn)在就好多了。 If you had studied hard before,you would be a college student now.如果你以前努 力學(xué)習(xí)的話,你現(xiàn)在早就是大學(xué)生了。 2.if省略句 在虛擬條件句中可省略if,把were,had,should提到句首,變?yōu)榈寡b句式。如: If I were at school again,I would study harder. →Were I at school again,I would study harder. 如果我還有上學(xué)的機(jī)會,我會更加努力地學(xué)習(xí)。 If you had come earlier,you would have caught the bus. →Had you come earlier,you would have caught the bus. 如果你來得早些,你就能趕上公共汽車了。 If it should rain tomorrow,we would not go climbing. →Should it rain tomorrow,we would not go climbing. 如果明天下雨的話,我們就不去登山了。 注意:若省略的條件狀語從句中的謂語動詞是否定形式時(shí),不能用動詞的縮略 形式。如:我們可以說Were it not for the expense,I would go abroad now.但不能 說Weren't it for the expense,I would go abroad now. 3.含蓄條件句 有時(shí)為了表達(dá)的需要,在虛擬語氣中并不總是出現(xiàn)if引導(dǎo)的條件句,而是通過 其他手段來代替條件句。如: What would you do with a million dollars(=if you had a million dollars)? 如果你有100萬美元,你會做什么? Without your help,we couldn't have finished the work ahead of time. =But for your help,...=If it had not been for your help,...=Had it not been for your help,... 沒有你的幫助,我們不可能提前完成這項(xiàng)工作。 I was ill that day.Otherwise,I would have taken part in the sports meeting.(副詞) 我那天病了。否則,我就參加運(yùn)動會了。 He telephoned to inform me of your birthday,or I would have known nothing about it.(連詞) 他打電話通知了我你的生日,否則,我對此一點(diǎn)都不知道。 I should have given you more help,but I was too busy.(連詞) 我本應(yīng)該多幫幫你,但我(那時(shí))太忙了。 4.even if,even though 也可用于虛擬語氣,其形式與if從句在虛擬語氣中的形式 相同。 二、虛擬語氣在名詞性從句中的運(yùn)用 1.用于賓語從句中 (1)wish后面的賓語從句一般用虛擬語氣,表示一種不可能實(shí)現(xiàn)的愿望。其謂 語動詞構(gòu)成形式為: ? 如: I wish(that)I were a bird and could fly freely in the sky. 我希望我是一只小鳥,能在天空中自由飛翔。 I wish(that)I had met that film star yesterday. 我希望昨天見到那個(gè)影星了。 How I wish it weren't raining now! 我多希望現(xiàn)在沒下雨啊! 此外,If only+句子=How I wish+that從句。如: If only I were a flying bird!=How I wish I were a flying bird! 我要是一只飛鳥該多好啊! If only I had seen the film!=How I wish I had seen the film! 我要是看了那部電影多好啊! (2)用于表示建議、愿望、命令等動詞后的賓語從句中,常見的動詞有:de- mand,order,require,insist,suggest,propose,advise等。賓語從句中的虛擬語氣結(jié) 構(gòu)為“should+動詞原形”,should可以省略。如: He suggested that we(should)start off early the next day. 他建議我們第二天早點(diǎn)出發(fā)。 They insisted that the boy(should)go with them. 他們堅(jiān)決主張那個(gè)男孩子跟他們一起去。 (3)在would rather后的賓語從句中,也用虛擬語氣,其構(gòu)成為would rather sb.+動 詞過去式/had done(從句動作先發(fā)生)。如: I would rather they didn't hear of the news. 我寧愿他們沒聽到那個(gè)消息。 (4)當(dāng)suggest表示“暗示,表明”之意,insist表示“堅(jiān)持說”之意時(shí),suggest/in- sist后的賓語從句不使用虛擬語氣,應(yīng)使用陳述語氣。如: The smile on his face suggested that he was satisfied with our work.他臉上的微 笑表明他對我們的工作很滿意。 The man insisted that he had never stolen the money. 那個(gè)人堅(jiān)持說他沒有偷錢。 在“It is desired/suggested/proposed/recommended/necessary/important/strange/ natural/a pity/essential+that從句”結(jié)構(gòu)中,從句的謂語動詞用“should+動詞原 形”,should可以省略。如: It is suggested that the meeting(should)be put off till next week.人們建議會議推 遲到下周。 It is strange that he (should)have acted toward his parents like that.(從句謂語動 詞動作在主句謂語動詞動作之前發(fā)生時(shí),從句謂語要用“should have+過去分 詞”,should可以省略) 真奇怪他竟然那樣對他的父母。 注意:以上句式也可以用陳述語氣。如: It's a pity that you can't dance. 2.用于主語從句中 真遺憾你不會跳舞。 3.用于表語從句和同位語從句中 在suggestion,proposal,order,plan,idea,request,advice等名詞后的表語從句和同 位語從句中要用虛擬語氣,其構(gòu)成是“should+動詞原形”,should可以省略。 如: My idea is that we(should)think it over before accepting it. 我的意見是在接受它之前我們要仔細(xì)考慮。 We all agreed to his suggestion that we (should)go to Dalian for sightseeing.我們 都同意他讓我們?nèi)ゴ筮B旅游的建議。 如果as if/as though引導(dǎo)的從句謂語動詞與主句謂語動詞所表達(dá)的動作同時(shí)發(fā) 生,從句用一般過去時(shí);如果as if/as though引導(dǎo)的從句謂語動詞所表達(dá)的動作 先于主句謂語動詞所表達(dá)的動作,從句用過去完成時(shí);如果as if/as though引導(dǎo) 的從句謂語動詞所表達(dá)的動作后于主句謂語動詞所表達(dá)的動作,從句謂語動 詞用would+動詞原形。如: He looks as if he were an artist.(同時(shí)) 他看起來像個(gè)藝術(shù)家。 She speaks English so fluently as if she had studied English in America.(先于) 她講英語如此流利,好像她在美國學(xué)過英語。 He learns English so hard as if he would go to the U.S.A.(后于) 他如此努力地學(xué)英語,好像他要去美國。 易混點(diǎn)總結(jié) 一、as if/as though用在虛擬語氣中 二、虛擬語氣用于定語從句中 It is(high)time(that)...句型中,定語從句的謂語動詞用過去式,或用“should+動 詞原形”(其中should不能省略)。此句型意為“(現(xiàn)在)該……”,用來表示提 議。如: It is(high)time that you went to school. 你該去上學(xué)了。 It is(high)time that we should start out. 我們該出發(fā)了。 高頻考點(diǎn)一 情態(tài)動詞表能力
can/could一般表示主語本身所具有的能力,意為:能,會;而be able to一般表示通 過努力能做到某事。 典例1????(2024浙江,4)It was so noisy that we ????hear ourselves speak. ?答案 couldn't ?解析 句意:這里如此嘈雜以至于我們無法聽到自己說話。根據(jù)語境可知此 處表達(dá)過去的能力故用couldn't。 考點(diǎn)清單 ? 高頻考點(diǎn)二 情態(tài)動詞表推測 情態(tài)動詞表推測分為:對現(xiàn)在情況和過去情況的推測、對情況肯定的推測、 否定的推測以及可能性的推測。對現(xiàn)在情況的肯定推測就用must,否定推測 就用can't,可能性推測就用can/could,may/might。對過去情況的肯定推測就用 must have done,否定推測就用can't have done,可能性推測就用can/could/may/ might have done。做題時(shí)要判斷是哪一種推測,還要判斷出是對現(xiàn)在還是對過 去情況的推測。 典例2????(2024重慶,12)You ????be Carol.You haven't changed a bit after all these years. ?答案 must ?解析 句意:你一定是卡蘿爾,這么多年過去了你一點(diǎn)也沒變。根據(jù)語境可 知此處表示對現(xiàn)在情況的肯定推測,所以要用must(一定)。 ? 高頻考點(diǎn)三 情態(tài)動詞表請求、許諾、允許 1.向?qū)Ψ教岢龌蛘髑笠庖姇r(shí)一般要用比較委婉的語氣,常用的句式有:Shall I/ he/they...?Could I...?May I...? 2.情態(tài)動詞shall用于第二、三人稱表示說話者命令、警告、許諾的語氣。表 示按照規(guī)章制度、法律、條例規(guī)定應(yīng)該怎么做也要用shall。這是高考對shall 的考查熱點(diǎn)。 典例3????(2024北京,27)????I have a word with you?It won't take long. ?答案 Can/May ?解析 句意:我能和你說句話嗎?不會花很長時(shí)間的。本題考查情態(tài)動詞的 基本用法。can/may可以,表請求允許。 ? 高頻考點(diǎn)四 情態(tài)動詞表必要性 must語氣最強(qiáng)烈,表示說話者堅(jiān)決認(rèn)為必須做某事;need語氣要比must弱,表示 說話者認(rèn)為有必要做某事;should在表示該含義時(shí),表示在義務(wù)上應(yīng)該做某 事。should還表示“竟然會,(將來)萬一”。 典例4????(2024北京,29)—Can't you stay a little longer? —It's getting late.I really ????go now.My daughter is home alone. ?答案 must ?解析????句意:——難道你不能再多逗留一會兒嗎?——時(shí)間不早了。我現(xiàn)在 確實(shí)得走了。我的女兒獨(dú)自一人在家。根據(jù)對話內(nèi)容可知空格處表示“必要 性”,故用must。 ? 情態(tài)動詞+have done 意義 must have done 想必/準(zhǔn)是/一定做了 否定式為can't/couldn't have done could have done 本來能夠做 can/could have done 過去可能會做 cannot/could not have done 1.過去不可能做 2.過去沒能夠做 may/might have done 也許/或許已經(jīng)做了……,一般只用于肯定句或否定句中(在否定句中表示“可能不”),不用于疑問句。用might則表示語氣更加不肯定 高頻考點(diǎn)五 情態(tài)動詞+have done should/ought to have done 本該做而實(shí)際上未做 shouldn't/ought not to have done 本不該做而做了 needn't have done 本來不必做而做了 had better have done 要是當(dāng)時(shí)做了就好了,用于事后的遺憾,含輕微的責(zé)備,其否定式had better not have done表達(dá)相反的含義 would rather have done 寧愿當(dāng)時(shí)做了,其否定式would rather not have done表達(dá)相反的含義,兩者都表示“后悔”之意 would like/love to have done 過去愿意做但未做成 典例5????(2024天津,7)I ????have worried before I came to the new school,for my classmates here are very friendly to me. ?答案 needn't ?解析 句意:在進(jìn)入這所新學(xué)校之前我本沒必要擔(dān)心,因?yàn)檫@里的同學(xué)對我 很友好。根據(jù)語境可知此處表達(dá)“過去對某事?lián)倪^,但現(xiàn)在看來這種擔(dān)心 沒有必要”,應(yīng)該用needn't have done。 ? 高頻考點(diǎn)六 虛擬語氣
虛擬語氣是用來表示與現(xiàn)在或過去的實(shí)際情況相反的假設(shè),近年來主要是考 查上述兩點(diǎn),而對將來可能情況的假設(shè)已很少涉及。注意下列幾種情況: 1.表示與現(xiàn)在實(shí)際情況相反的假設(shè):條件從句謂語動詞應(yīng)該用一般過去時(shí)(be 動詞用were),主句謂語動詞要用should/might/would/could+動詞原形。 2.表示與過去實(shí)際情況相反的假設(shè):條件從句謂語動詞應(yīng)該用過去完成時(shí),主 句謂語動詞要用should/might/would/could have done。 3.用其他形式來代替條件從句,常見的有:without,otherwise,but for等。 4.一些特殊動詞后的that從句中謂語動詞要用(should+)動詞原形,常常考查把 should去掉的情況。與這些特殊動詞相關(guān)的名詞形式后的that引導(dǎo)的同位語 從句的謂語動詞也符合這一原則。 5.需要特別注意的幾個(gè)結(jié)構(gòu):wish句式,as if/though句式,would rather...,It's high time...等。 典例6????(2024北京,34)If I ????(see)it with my own eyes,I wouldn't have be- lieved it. ?答案 hadn't seen ?解析 句意:如果不是我親眼看到,我是不會相信的。由主句謂語“wouldn't
have believed”可知此處為與過去事實(shí)相反的假設(shè),故if從句謂語動詞應(yīng)為 hadn't seen。 ? 知識清單一 情態(tài)動詞的用法要點(diǎn) 一、表能力 ? 如: I am starving to death.I can eat two bowls of rice now.(現(xiàn)在的能力) 我快餓死了,現(xiàn)在我能吃兩碗米飯。 If you have a good sleep,you will be able to work out this problem.(將來的能力) 知識清單 如果你好好睡一覺,你將能夠解出這道題。 The fire spread through the hotel very quickly but everyone was able to get out. (過去有能力做并且成功地做了某事) 盡管這場大火迅速蔓延到了整個(gè)賓館,但是每個(gè)人都逃了出去。 I could have worked out the problem,but I was too nervous.(過去有能力做但未 做) 我本來可以解出這道題,但我太緊張了。 1.可能性可分為客觀的可能性和具體事情實(shí)際發(fā)生的可能性兩種。所謂客觀 的(理論的)可能性即并不涉及具體某事是否會發(fā)生,此種用法常常可以說明人 或事物的特征。情態(tài)動詞can可用于肯定句中表示客觀的(理論的)可能性,而 表示具體事情實(shí)際發(fā)生的可能性時(shí),can 一般不用于肯定句。如: Accidents can happen on such rainy days. 在這樣的多雨天里可能會發(fā)生事故。(客觀的可能性) We may go to the cinema tonight,but we are not sure yet. 今晚我們可能去看電影,但還沒確定。(實(shí)際可能性,不用can) 2.表示具體事情實(shí)際發(fā)生的可能性: (1)表示具體事情實(shí)際發(fā)生的可能性的層次比較(見下表) 二、表推測(可能性) 詞形 肯定式 否定式 疑問式 must 必定,必然 / / should 按說應(yīng)該 應(yīng)該不會 / ought to 按說應(yīng)該 應(yīng)該不會 / can / 不可能 有可能嗎? could 微弱的可能 不可能 語氣比 can弱 may 或許,也許,也未 可知,也說不定 可能不 / might 比may還弱 比may not 還弱 / (2)表示具體事情實(shí)際發(fā)生的可能性時(shí),may,must常用于肯定句,一般不用于否 定句和疑問句(may not表示“可能不”);can 常用于否定句、疑問句或感嘆句 中,表示疑惑、驚訝或不相信等意思;could既可用于肯定句又可用于否定句、 疑問句中。如: This can't/couldn't be done by him. 這不可能是他干的。(表不相信) This may not be done by him. 這可能不是他干的。(表不確定) He could be on his way home now. 他現(xiàn)在可能在回家的路上了。(could 不如may/might常用) Can this be done by him? 這可能是他干的嗎?(表示疑惑、驚訝) Mr.Bush is on time for everything.How can it be that he was late for the opening ceremony? 布什先生做一切事情都非常守時(shí)。開幕式他怎么可能會遲到呢?(表示疑惑、 驚訝) I didn't hear the phone.I must have been asleep. 我沒聽見電話鈴響。我一定是睡著了。(表肯定) —Are you coming to Jeff's party? —I'm not sure.I might go to the concert instead.(表不確定) ——你要來杰夫的聚會嗎? ——我不確定。我可能要去音樂會。 (3)could,might并不一定與過去的時(shí)間有關(guān),而表示可能性弱于它們相應(yīng)的現(xiàn) 在時(shí)形式。如: This may/might be done by him. 這件事有可能是他干的。(語氣依次遞減) (4)should表推測時(shí),表示確定或可能有的未來或期望,即合乎理想的情況或結(jié) 果。如: He ought to/should be here on time—he started early enough. 他(應(yīng))該按時(shí)到這里——他出發(fā)得夠早的了。 We should arrive before dark. 我們按說能在天黑前到達(dá)。 The roads should be less crowded today. 按說今天路上就不那么擁擠了。 三、表示請求、允許、允諾 1.當(dāng)對方是決策者時(shí),你代表你(們)自己(I,we),或代表第三者(he,she,they)向?qū)?方(you)請示或提出建議時(shí)用:①Shall/May(Might)/Can(Could)I/we...?②Shall he /she/they...?③Would/Will you...?如: Shall the driver wait outside? 司機(jī)在外邊等著可以嗎? When shall my father be able to leave hospital? 我父親什么時(shí)候可以出院? Would you do me a favor? 請幫我一下,好嗎? 2.could/might/would/should表委婉的語氣。如: —Could/Might I use your bike tomorrow morning? —Yes,you can/may.(否定:No,I'm afraid not.) ——明天早晨我用一下你的自行車,行嗎? ——行,你用吧。(否定:不,恐怕不行。) 不可以說:Yes,you could/might.回答允許時(shí),用could/might表委婉是不恰當(dāng)?shù)摹?3.shall與第二、三人稱連用,用于陳述句,表示說話者的命令、警告、威脅;當(dāng) 宣布法律規(guī)定時(shí),也用shall。 You shall leave the room at once,and he also shall.(=I order you and him to leave the room at once.) 你馬上離開這個(gè)房間,他也一樣。(說話者的命令) It has been announced that candidates shall remain in their seats until all the pa- pers have been collected. 據(jù)宣布,在所有試卷收上來之前,應(yīng)試者必須待在自己的座位上。(規(guī)則或規(guī) 定) 四、表示必要性 1.must 常用來表示必要性,意為“必須”,must do sth.(現(xiàn)在或?qū)?必須做某 事。 2.don't have to do sth./don't need to do sth./needn't do sth.(現(xiàn)在或?qū)?不必做 某事。 3.表示過去沒必要做某事時(shí),分為以下情況: (1)needn't have done sth.本來不必做而做了某事 (2)didn't have to do sth./didn't need to do sth./It was not necessary to do sth.(過 去)不必做(不強(qiáng)調(diào)是否做了)某事 You needn't have worked that late last night.It was harmful to your health. 你昨晚本不必工作到那么晚。那對你的身體沒好處。 —Did you work very late last night? —No,I didn't.I didn't need to work very late. ——你昨天晚上工作到很晚嗎? ——不是很晚。我沒必要工作到很晚。 4.should也可以表示必要性,意為“(義務(wù)上)應(yīng)該”。should表示必要性時(shí),在 語氣上比must(必須)弱。“should+動詞原形”表示現(xiàn)在或?qū)響?yīng)該做(的必 要性);“should+have+過去分詞”表示過去本該做(的必要性)。如: I should go and visit him this afternoon,but I wonder if I will be free. 今天下午我應(yīng)該去看望他,但我不知道我是否有空。(表示將來的必要性) You should have come to the conference yesterday.What was the reason for your absence? 你昨天本應(yīng)該參加那個(gè)會議。你缺席的原因是什么?(表示過去的必要性) 五、表示“寧愿做某事”時(shí),可使用下面這些句式: ? ? 高考中對這類用法的考查主要側(cè)重結(jié)構(gòu),因此要熟記其結(jié)構(gòu)。 情態(tài)動詞+have done 用法 例句 must have done 想必/準(zhǔn)是/一定做了否定式為:can't/couldn't+have done It must have rained last night,for the road is quite muddy.昨晚一定下雨了,因?yàn)槁泛苣酀簟?can/could have done 1.本來能夠做 2.過去可能會做 Can he have gone to his aunt's? 他有可能去他姨媽家了嗎? cannot/could not have done 1.過去不可能 2.過去沒能夠 He cannot have forgotten it. 他不可能忘了那件事。 六、“情態(tài)動詞+have done”用法一覽表 may/might have done 也許/或許已經(jīng)做……,一般只用于肯定句或否定句中(在否定句中表示“可能不”),不用于疑問句中。might則表示語氣更加不肯定。 It's too late.I think he may have gone to bed.太晚了,我想他或許已經(jīng)睡了。 He may not have finished the work.他也許還沒完成那項(xiàng)工。 should/ought to have done 本該做而實(shí)際上未做 You ought to have done this exercise more carefully.你本應(yīng)該更仔細(xì)地做這個(gè)練習(xí)。 should not/ought not to have done 本不該做而做了 You shouldn't have told her the truth. 你本不該告訴她真相。 needn't have done 本不必做而做了 You needn't have taken a taxi here,for it was very near to my house.你本來不必打車來這里 的,因?yàn)殡x我家很近。 had better have done 當(dāng)時(shí)最好做了(其否定式had better not have done表達(dá)相反 的含義) You had better not have scold- ed her. 要是那時(shí)你沒責(zé)罵她就好 了。 would rather have done 寧愿當(dāng)時(shí)做了(其否定式 would rather not have done表 達(dá)相反含義,兩者都有“后 悔”之意) I raised objections at the meet- ing,but now I would rather not have done that. 我在會上提出了反對意見,但 現(xiàn)在我寧愿沒那么做。 would like/love to have done sth. 過去愿意做但未做成 I would love to have gone to the party last night,but I had to work extra hours to finish a re- port. 昨晚我本來很想去參加聚會 的,但我得加班完成一個(gè)報(bào) 告。 七、情態(tài)動詞的其他用法要點(diǎn): 1.cannot but+do sth.表示“不得不,只好做某事”。如: I cannot but choose to go.我只好去。 2.may well和may as well結(jié)構(gòu)。 “may well+動詞原形”是一種常用結(jié)構(gòu),意為“完全能,很可能”,相當(dāng)于“be very likely to+動詞原形”。如: He may well be proud of his son. 他大可為他的兒子感到自豪。 Her appearance has changed so much that you may well not recognize her. 她的模樣變化太大,你很可能認(rèn)不出她了。 “may as well+動詞原形”意為“最好,不妨,倒不如”。如: You may as well do it at once.你最好馬上就做這件事。 We may as well stay where we are. 我們留在現(xiàn)在的地方倒也不錯。 3.cannot(或can never)與enough連用表示“再……也不為過”。(具體用法見 形容詞和副詞專題。) 4.may可以用于祈使句,表示祝愿。如: May we never forget each other.愿我們彼此永不相忘。 May you return in safety.愿你平安歸來。 5.“Why/How+should”結(jié)構(gòu)表示說話人對某事不能理解,感到意外、驚訝等, 意為“竟會”。如: Why should you be so late today?你今天怎么來得這么晚? How should I know?我怎么會知道?(意為:我不知道。) 6.must表示“偏要,硬要”。如: Must you make so much noise? 你非得弄出這么大聲響嗎? 7.may作“可以”講時(shí),其否定式常用“mustn't”表示“禁止”;must作“必 須”講時(shí),其否定式是“needn't”,表示“不必”。如: —May I use your car? —No,you mustn't. ——我能用用你的車嗎? ——不,一定不能。 (委婉的拒絕可用:Sorry,but I am using it now.或You'd better not.等) —Must I work out the problem tonight? —No,you needn't. ——我今晚必須做出這道題嗎? ——不,不必。 8.need和dare的用法 need和dare兩者既可用作情態(tài)動詞也可用作實(shí)義動詞。作實(shí)義動詞時(shí),有人稱 和數(shù)的變化,可用于肯定句、否定句或疑問句中,構(gòu)成否定句或疑問句時(shí)要用 助動詞do,does,did;作情態(tài)動詞時(shí),沒有人稱和數(shù)的變化(dare的過去式為dared), 直接接動詞原形,多用于否定句和疑問句中,構(gòu)成否定句和疑問句時(shí)不用助動 詞。 另外,dare作情態(tài)動詞時(shí),還可用于條件狀語從句中,過去式為dared;作實(shí)義動詞 時(shí),dare用于疑問句或否定句,后面的to也可省略;I dare say是習(xí)慣說法,意為 “我想,大概”。如: He needn't do it.(情態(tài)動詞) He doesn't need to do it.(實(shí)義動詞) 他不必做這件事。 I didn't know whether he dared say that to him.(情態(tài)動詞,有時(shí)態(tài)變化) 我不知道他是否敢對他說那件事。 He didn't dare(to)do it.(實(shí)義動詞) He dared not do it.(情態(tài)動詞) 他不敢做這件事。 注意:need作實(shí)義動詞時(shí),還可表示“需要”,后接動名詞的主動形式表示 被動含義(詳見非謂語動詞專題)。如: The floor needs sweeping. 這地需要打掃了。 知識清單二 虛擬語氣 一、虛擬語氣在非真實(shí)條件句中的運(yùn)用
從句 主句 例句 與現(xiàn)在事實(shí)相反的假 設(shè) If+主語+動詞的過去 式(be動詞用were) 主語+should/would/ could/might+動詞原 形 If I were you,I should seize the chance to go abroad. 如果我是你,我就抓住 這次出國的機(jī)會。
