【文章內(nèi)容簡介】 y／ might be your mother． ，語氣要比 can委婉，但在回答問題時我們不能用 could,因為語氣委婉，可能性就變小了。如： —Could I use your telephone？ —Yes, please go ahead． ，我們要用 was／ were able to而不能用 could。如： It was a holiday and the children were able to go to the seaside． The girl worked hard so she was able to pass the final test． 4． must與 have to都可以表示 “必須 ”的意思，但要注意以下兩點區(qū)別。 1) must只有現(xiàn)在時，而 have to有現(xiàn)在時、過去時和將來時。如： We must work hard, or we’ll fail in the examination． Years ago, the poor girl had to leave school for lack of money． 2) must表示主觀看法， have to則側(cè)重于客觀需要。如： We must be strict with ourselves in everything． In cities with many cars, some people have to wear masks． 5． must表示推測時，其反意問句有好幾種形式。 1) “must＋動詞原形 ”對目前的情況進行推測時以及用 must＋ be＋ ing 形式對目前正在發(fā)生的情況進行推測時，疑問短語部分要與 must之后的動詞相一致。如： The mathematics teacher must be in the office now, isn’t he﹖ 2) “must＋ have＋過去分詞 ”用來表示對已經(jīng)發(fā)生的事情進行推論。如果句子中有過去的時間狀語，疑問部分用助動詞 didn’t否則，疑問部分用 haven’t或 hasn’t。如： The children must have watered the tomatoes yesterday, didn’t they﹖ The minister must have arrived in Shanghai, hasn’t he﹖ 6． shall可以用來征求對方意見，用于第一、三人稱。此外它也可以用來表示說話人的命令、警告、允諾、威脅或決心等，這時它用于第二、三人稱。如： Shall she go to the concert with us this evening﹖ (征求意見 ) You shall go to the front at once． (命令 ) Don’t worry． You shall get the answer this very afternoon．（允諾） He shall be sorry one day． I tell you． (警告 ) Nothing shall stop us from fighting against pollution． (決心 ) 7．在表示將來的時間、條件狀語從句中，不能用 will（這時的 will不是情態(tài)動詞，而是助動詞，幫助構(gòu)成將來時）。如： If it will rain tomorrow, we shall not go to the mountain village． (誤 ) If it rains tomorrow, we shall not go to the mountain village． (正 ) 當(dāng)情態(tài)動詞 will表示意愿或決心時，是可以用于條件狀語從句的。如： If you will listen to me, I’ll give you some advice on how to learn English． 如果你愿意聽我的話，我將給你提點學(xué)習(xí)英語的建議。 If you will e this way， the manager will meet you． 請您往這邊走，經(jīng)理現(xiàn)在要見你。 8． should除表示必要或義務(wù)外，還可表示推測或可能。如： The American friends should be here now． “should／ ought to＋ have＋過去分詞 ”既可表示本該做而事實上沒有做的事，也可以表示驚訝、責(zé)備、贊嘆等情緒。如： You should have told her about it the day before yesterday． It’s wonderful that you should have achieved so much in these years． “情態(tài)動詞＋ have＋過去分詞 ”是很重要的一種句型，除 should外， may, might, must, couldn’t, needn’t, ought to等都可以用于這一句型，但要注意使用不同的情態(tài)動詞句子的意思就有所不同。 9． ought to與 should意思接近，大多數(shù)情況下二者可以互換，但是 should談的是自己的主觀看法， ought to則更多反映客觀情況，在談 到法律、義務(wù)和規(guī)定時使用。如： We should／ ought to help each other and learn from each other in our work． She is your mother, so you ought to support her． We ought to go and see Mary tomorrow, but I don’t think we will． 10． need用作情態(tài)動詞，僅用于否定句和疑問句，而不用于肯定句。在肯定句中要用 must, have to, should, ought to或?qū)?need當(dāng)作行為動詞使用。如： We need report the matter to the boss immediately． (誤 ) We must report the matter to the boss immediately．（正） We need to report the matter to the boss immediately．（正） dare的用法也一樣。 dare與 need 的用法 1) dare作為情態(tài)動詞 ,主要用于疑問句 ,否定句和條件 從句中 ,一般不用于肯定句。 a. How dare you say I’m unfair? b. He daren’t speak English before such a crowd, dare she? c. If he dare break the rule, he will be punished. 2) need表示 ”需要 ”或 ”必須 ”,作情態(tài)動詞用時 ,僅用于否定句或疑問句、條件從句中。 “有 ……必要 ”。在肯定句中一般用 must, have to, ought to或 should代替。 a. You needn’t e so early. b. —Need I finish the work today? —Yes, you must. / No, you needn’t. c. If you need go there, please let me know. 3) dare和 need常用作實義動詞 ,有時態(tài)、人稱和數(shù)的變化。所不同的是 ,在肯定句中 , dare 后面通常接帶 to的不定式 。 在否定和疑問句中 , dare后可接帶 to或不帶 to的不定式。 a. I dare to swim across the river b. He doesn’t dare (to) answer. c. We need time and money. d. The dining room needs/ wants/ requires cleaning every day. = The dining room needs/ wants/ requires to be cleaned every day. e. Does he need to take the medicine four times a day? 需要注意的幾點 : 1. 表示猜測， can 一般不用于肯定句中，除非是 “經(jīng)驗之談 ” 。這時 can 可以表示客觀的可能性 ,并不牽涉具體的事情是否會發(fā)生 。要表示某事發(fā)生的可能性別時需要用 could， may， might。 Children can often get ill suddenly．（小孩常?？赡芡蝗簧。? Certain things in the home can be dangerous， especially if you have young children．（家里的某些東西可能有危險，尤其是有小 孩的時候。）上面兩句可以看作醫(yī)務(wù)工作者或撫養(yǎng)過孩子的人說的話，屬 “經(jīng)驗之談 ”。 Accidents can happen on such rainy days. 2． may和 might都不用于疑問句中。如： （正） Can／ Could it be cloudy tomorrow？ （誤） May／ Might it be cloudy tomorrow？ 3． must的否定式是 can39。t／ couldn39。t，不是 needn39。t或 mustn39。t。 4． would ＋ V原形：想必現(xiàn)在／過去 …… ；現(xiàn)在／過去可能 …… He would be back today／ yesterday．想必他今天／昨天回來了。（他今天／昨天可能回來了。） 5． should／ ought to＋ V原形：想必現(xiàn)在／將來會 …… The dinner should／ ought to be ready now．想必晚飯現(xiàn)在已備好。 He should／ ought to ring up this afternoon．想必他今天下午會打電話的。 6． will ＋ V原形：將來一定／準(zhǔn)會 …… Try your best， and your wish will e true．盡力吧，你的理想準(zhǔn)會實現(xiàn)的。 【強化訓(xùn)練】 1. Black holes ______ not be seen directly, so determining the number of them is a tough task. A. can B. should C. must D. need 2． — What’s the name? — Khulaifi. _______ I spell that for you? A. Shall B. Would C. Can D. Might 3. — Must he e to sign this paper himself? —Yes, he A. need B. must C. may D. will 4. There39。s no light on —they______ be at home. A. can39。t B. mustn39。t C. needn39。t D. shouldn39。t 5. Some aspects of a pilot’s job __________be boring, and pilots often _________work at inconvenient hours. A. can。 have to B. may。 can C. have to。 may D. ought to。 must 6. —Mum, I’ve been studying English since 8 o’clock. I go out and play with Tom for a while? —No, I’m afraid not. Besides, it’s raining outside now . A． Can’t B． Wouldn’t C． May not D． Won’t 7. Children under 12 years of age in that country ________ be under adult supervision when in a public library. A. must B. may C. can D. need 8. —May I smoke here? —If you ____, choose a seat in the smoking section. A. should B. could C. may D. must 9. The weather turned out to be fine yesterday． I___the trouble to carry my umbrella with me． A． should have taken B． could have taken C． needn39。t have taken 39。t have taken 10. “The interest be divided into five parts, according to the