Modalverbs(Ⅱ)

1、GRAMMAR GUIDEModal verbs ()n ought to, have to, mustnt，neednt尋規(guī)找矩 觀察下列三組句子，注意情態(tài)動(dòng)詞ought to， have to， mustnt和neednt的不同用法。1. ought to1) You oughtnt to make private phone calls in work time.在工作時(shí)間你不應(yīng)該打私人電話。2) He ought to be there by now.他現(xiàn)在應(yīng)該到那兒了。3) Ought I to write to apologize to her？我應(yīng)該向她寫信道歉嗎？4) They

2、 ought to come tomorrow, oughtnt they (= shouldnt they)? 他們應(yīng)該明天來，是嗎？2. have to1) My brother was very ill, so I had to call the doctor in the middle of the night.我弟弟病得很厲害，我只得半夜里把醫(yī)生請(qǐng)來。2) Must I finish the task right now？我現(xiàn)在必須完成這項(xiàng)任務(wù)嗎？Yes, you must. / Yes, you have to. 是的，你必須。（No, you neednt. / No, you

3、dont have to. 不，不必。）3) You dont have to tell him about it.你不必把此事告訴他。4) Do you have to go now. 你現(xiàn)在就得去嗎？Yes, I do. 是的，我必須去。3. mustnt與neednt1) Smoking must not be allowed in the office.嚴(yán)禁在辦公室吸煙。2) Must we hand in our exercises today?我們今天必須交作業(yè)嗎？Yes, you must. 是的，必須交。（No, you neednt (you dont have to).不，

4、不必今天交。）3) It must be that naughty boy crying outside.肯定是那個(gè)調(diào)皮的孩子在外面大叫。It cant be him, because he has gone to school.不可能是他，因?yàn)樗呀?jīng)去上學(xué)了。4) There are still one and a half hours to go. We neednt be in such a hurry. 還有一個(gè)半小時(shí)，我們不必如此慌慌張張。歸納總結(jié)通過觀察分析以上幾組例句，我們可以對(duì)ought to, have to, mustnt和neednt的用法歸納如下：1. ought to

5、 意為“應(yīng)當(dāng)；應(yīng)該”，一般可與should互換，但ought to語氣更強(qiáng)，且多與責(zé)任、義務(wù)相關(guān)。如例1、4。 否定式是ought not to或oughtnt to。如例1； 可以表示猜測(cè)。如例2； 疑問式是將ought提前。如例3； 在變?yōu)榉匆庖蓡柧鋾r(shí)，疑問部分用ought或should。如例4。2. have to 表示一種客觀的需要，意思是“不得不”。 如例1； 有人稱、數(shù)和時(shí)態(tài)的變化。如例1; 否定形式是dont / doesnt / didnt have to，相當(dāng)于neednt。如例2、3; 疑問式是在其前面用助動(dòng)詞do / does / did。如例4。3. mustnt 與n

6、eednt mustnt表示禁止。如例1； 用must提問時(shí)的否定回答須用neednt / dont have to。如例2； mustnt與dont have to的意思大不相同，前者表示“禁止”，意思是“一定不能”；后者表示“沒有必要”，意思是“不必”，相當(dāng)于neednt。如例2； must常用于肯定句中表示猜測(cè)、推測(cè)，意為“一定”；表示“不可能”時(shí)要用cant。如例3； need用于否定句和疑問句中意為“必要”。如例4。學(xué)以致用用以上情態(tài)動(dòng)詞的適當(dāng)形式填空。1. One cross the street against the red light.2. His mother is ill, so he take care of her.3. I have to stay at home preparing my lessons.But you . Tomorrow is Sunday.4. Mikes father is ill, but you tell him, because he is t