酷兔英语

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    情态动词 (Model Verbs) 又称为情态助动词 (Model Auxil-iaries)。英语中助动词主要有两类:一是基本助动词,如have, do, be;二是情态助动词,如may, must, need等。情态动词与其他动词连用表示说话人的语气。情态动词可表达建议、要求、可能和意愿等。情态动词没有人称和数的变化。在大学英语四、六级考试中,情态动词部分重点测试以下内容:

    1)情态动词+行为动词完成式

    2)情态动词+行为动词进行式

    3)情态动词+行为动词完成进行式

    4)某些情态动词的特殊用法

    一、情态动词+行为动词完成式

    情态动词+行为动词完成式即“情态动词+ have + v-ed分词”,表示对过去行为或动作进行推测、评论或判断。

    1. must have v-ed

    must have v-ed 表示推测过去某事“一定”发生了。其否定形式为:cant / couldnt have v-ed, 表示过去不可能发生某事。例如:

    1Since the ditch is full of water, it must have rained last night.

    2You couldnt have met my grandmother. She died before you were born.

    2. could have v-ed

    could have v-ed 表示推测过去某动作“很可能”发生了。例如:

    1The dictionary has disappeared. Who could have taken it?

    2Tom could have taken it. He was alone yesterday.

    3.may / might have v-ed

    may / might have v-ed 表示推测过去某事“也许”发生了.may might 表示的可能性在说话人看来稍大些。例如:

    I cant find my keys. I may / might have left them at the school yesterday.

    4. ought to / should have v-ed ought not to / shouldnt have v-ed

    ought to / should have v-ed ought not to / shouldnt have v-ed 用于对已发生的情况表示“责备”、“不满”,分别表示“本应该…”和“本不应该…”。例如:

    1With all the work finished, I should have gone to the party last night.

    2You ought not to make fun of him. He is not the one you laugh at but learn from.

    5. neednt have v-ed

    neednt have v-ed 表示过去做了某事,但没有做的必要, 意为“本没必要…”。例如:

    You neednt have waken me up; I dont have to go to work today.

    注:表示推测过去某动作发生的可能性时,就表示的可能性程度而言,must最大,could其次,may更次之,might最小。例如:

    I wonder how Tom knew about your past.

    He must / could / may / might have heard of it from Mary.

    二、情态动词+行为动词进行式

    情态动词+行为动词进行式(即情态动词+ be + v-ing形式),表示推测或评论某动作现在是否正在进行。例如:

    1He must be playing basketball in the room.

    2She may be staying at home.

    三、情态动词+行为动词完成进行式

    情态动词+行为动词完成进行式(即情态动词+ have been + v-ing 形式),表示推测或评论过去某动作是否正在进行或一直在进行。例如:

    1They should have been meeting to discuss the problem.

    2He may / might have been buying stamps in the post office when you saw him.

    四、某些情态动词的特殊用法

    1. need

    考试中主要测试 need 作情态动词与作实义动词的区别,对此,可参见表1.need 作情态动词时,后面跟不带to 的动词不定式,即 need to。通常用在疑问句和否定句中,表示询问是否有“必要”,其否定形式为neednt,表示“不必”;疑问形式为 Need do? 极少用于肯定句。例如:

    1I dont think we need turn the light on at that time.

    2Need you ride a bike to school?

    情态动词need与实义动词need 在时态、肯定、否定结构上的对比见表1

    2. dare

    考试中主要测试dare作情态动词和作实义动词的区别。

    情态动词dare 与实义动词dare 在时态、肯定、否定、疑问结构上的对比见表2

    3. can may

考试中主要测试canmaycouldmight表示可能性的区别及对may构成的疑问句的回答。

 

时态      情态动词need               实义动词 need

      You need (not) do      You (dont) need to do           

     

      He need (not) do       He needs (doesnt need) to do

 

                             You needed (didnt need) to do 

    

                             He needed (didnt need) to do

 

     You need (not) do       You will (not) need to do

 

     He need (not) do        He will (not) need to do

 

 

 

 

 句型    时态                     动词  

                  情态动词dare           实义动词 dare

肯定句  现在时  dare to 少用           dare/dares to do

        过去时  dare to 少用           dared to do

否定句  现在时  darent/dare not do    do/does not dare (to) do 

        过去时  dared not do           did not dare (to) do

疑问句  现在时  Dare he do?             Do you/Does he dear (to) do?

        过去时  Dared he do?           Did he dare (to) do

    1can, could, may, might都可以表示可能性.can, could表示潜在的可能性或理论上或逻辑判断上存在的可能性;而may, might则表示事实上的可能性。此外,can还具有“有能力”的意思,而maymight则不具此意。例如:

    1According to the weather forecast, it may rain tomorrow.

    2) Any man with a little sense can see that he is wrong.

   2May I / we …?这一类疑问句的肯定回答为Yes, please.Certainly;否定回答为Please dont.No, you mustnt. 例如:

    May we leave now? No, you mustnt. You havent finished your home work yet.

    4. can be able to

    can be able to 都可以表示能力,但两者在用法上有点差异:can (could)表示主观能力,不表示意愿,它的将来时用will be able to; be able to表示主观意愿,强调要克服困难去做某事。例如:

    1My grandma is over seventy, but she can still read without glasses.

    2He is able to give up his bad habits.

    5. must have to

    must have to 都可以表示“必须”,但有几点区别:

   1must 强调“内在的职责”、“义务”,而have to 强调“外界压力”、“不得已而为之”。

   2have to可用于多种时态,而must一般用于现在时,其过去时与将来时分别由had toshall / will have to代替。

   3)在回答must引起的问题时,如果是否定的答复,不能用mustnt,而要用needntdont have to,因为mustnt是“一定不要”、“一定不能”的意思。例如:

    1You must come to the classroom before eight.

    2It is raining hard outside, but I have to leave now.

    3Must we do it now? No, you neednt.

    6. used to +v, be used to +v-ingbe used to +v

   1used to +v意为“过去常常”,“过去一直”;be used to +v-ing / n(名词)意为“习惯于”;be used to +v意为“被用来(做某事)”。

   2used to只表示过去,而be used to +v-ing / n可表示现在、过去或将来。例如:

    1He used to smoke. Now he doesnt.

    2Hes quite used to hard work / working hard.

    3The knife is used to cut bread.

    7.用作情态动词的其他短语

    would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情态动词。例如:

    1The soldier would sooner die than surrender.

    2The brave soldier would as soon die as yield to such an enemy.

    3Id rather walk than take a bus.

    4If you dont like to swim, you may just as well stay at home.

    注:这些短语后一般直接跟动词原形.would (had) rather, would (had) sooner, would (just) as soon后可跟that 引导的从句,that 常省去,从句要用虚拟语气。对现在和将来的假设用过去时,对过去的假设用过去完成时。例如:

    1I would rather you came on Sunday.

 

    2I would sooner you hadnt asked me to speak yesterday.


生词表:
  • grandmother [´græn,mʌðə] 移动到这儿单词发声  n.(外)祖母   (初中英语单词)
  • working [´wə:kiŋ] 移动到这儿单词发声  a.工人的;劳动的   (初中英语单词)
  • yesterday [´jestədi] 移动到这儿单词发声  n.&ad.昨天;前不久   (初中英语单词)
  • grandma [´grænmɑ:] 移动到这儿单词发声  n.奶奶;外婆   (高中英语单词)
  • forecast [´fɔ:kɑ:st] 移动到这儿单词发声  vt.&n.预测;预报   (英语六级单词)



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