第2个回答 2011-06-11
情态动词有哪些及用法
情态动词 (Model Verbs) 又称为情态助动词 (Model Auxil-iaries), 主要有can, may, must, could, might, shall , should, will, would, ought to, need, dare等(过去式更委婉哦!)。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。情态动词部分重点测试以下内容:
(1)情态动词+动词完成式: must have done
(2)情态动词+动词进行式: must be doing
(3)情态动词+动词完成进行式: must have been doing
(4)某些情态动词的特殊用法: need
一、情态动词+动词完成式
情态动词+动词完成式即“情态动词+ have + done分词”,表示对过去行为或动作进行推测、评论或判断。
1. must have done
must have done 表示对过去某事的肯定猜测。其否定或疑问形式都用can(could) 来表示.
例如: Since the road is wet, it must have rained last night.
He can’t have missed the way. I drew him a map.
“The dictionary has disappeared. Who could have taken it?”
当然对现在发生或将来发生的事情,要用must do 表示猜测, 否定为can’t do.
He must understand that we mean business.
You must be hungry after a long walk.
2.may / might have done
may / might have done 表示推测过去某事“也许”发生了.may 比 might 表示的可能性在说话人看来稍大些。例如:
I can’t find my keys. I may / might have left them at the school yesterday.
3. could have done 在肯定句型中, 往往用作委婉的批评. 本应该做什么,而没做; 有时也用作猜测.
You could have told us earlier.
Tom could have taken the dictionary.
4. ought to / should have done和 ought not to / shouldn’t have done
ought to / should have done 和 ought not to / shouldn’t have done 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:
1)With all the work finished, I should have gone to the party last night.
2)You ought not to have made fun of him. He is not the one you laugh at but learn from.
5. needn’t have done
needn’t have done 表示过去做了某事,但没有做的必要, 意为“本没必要…”。例如:
You needn’t have waken me up; I don’t 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+动词进行式
情态动词+行为动词进行式(即情态动词+ be + doing形式),表示推测或评论某动作现在是否正在进行。例如:
1)He must be playing basketball in the room.
2)She may be staying at home.
三、情态动词+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:
1)They should have been meeting to discuss the problem.
2)He 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。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下表。
时态 情态动词need 实义动词 need
现在时
He need (needn’t) do
Need he do….?
He needs (doesn’t need) to do
过去时
He needed (didn’t need) to do
将来时
He need (needn’t) do
Need he do….?
He will (not) need to do
注: need 一般用于否定句或疑问句.
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下 表。
句型 情态动词dare 实义动词 dare
肯定句
现在时 dare to 少用
过去时 dare to 少用
现在时 dare/dares to do
过去时 dared to do
否定句
现在时 daren’t/dare not do
过去时 dared not do
现在时 do/does not dare (to) do
过去时 did not dare (to) do
疑问句
现在时 Dare he do?
过去时 Dared he do?
现在时 Do you/Does he dear (to) do?
过去时 Did he dare (to) do
3. can 和 may
考试中主要测试can,may或could,might表示可能性的区别及对may构成的疑 问句的回答。
(1)can, 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may与might则不具此意。例如:
According to the weather forecast, it may rain tomorrow.
Any man with a little sense can see that he is wrong.
(2)May I / we …?这一类疑问句的肯定回答为Yes, please.或Certainly;否定回答为Please don’t.或No, you mustn’t. 例如:
“May we leave now?” “No, you mustn’t. You haven’t finished your home work yet.”
4. can 和 be able to
can 与 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:
1)My grandma is over seventy, but she can still read without glasses.
5. must 和 have to
must 和 have to 都可以表示“必须”,但有几点区别:
(1)must 强调“内在的职责”、“义务”,而have to 强调“外界压力”、“不得已而为之”。
(2)have 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 to与shall / 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mustn’t,而要用needn’t或don’t have to,因为mustn’t是“一定不要”、“一定不能”的意思。例如:
You must come to the classroom before eight.
2)It is raining hard outside, but I have to leave now.
3)“Must we do it now?” “No, you needn’t.”
6. used to +do, be used to +doing和be used to +do
(1)used 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)”。
(2)used 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:
1)He used to smoke. Now he doesn’t.
2)He’s quite used to hard work / working hard.
3)The 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:
1)The soldier would sooner die than surrender.
2)The brave soldier would as soon die as yield to such an enemy.
3)I’d rather walk than take a bus.
4)If you don’t 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:
1)I would rather you came on Sunday.
2)I would sooner you hadn’t asked
反义疑问句(The Disjunctive Question) 即附加疑问句。它表示提问人的看法,没有把握,需要对方证实。 反义疑问句由两部分组成:前一部分是一个陈述句,后一部分是一个简短的疑问句,两部分的人称时态应保持一致。
1.陈述部分肯定式+疑问部分否定式 可记为 前肯后否
2.陈述部分否定式+疑问部分肯定式 可记为 前否后肯
句子类型:一种是反义的附加疑问句,一种是非反义的附加疑问句。
用法
(1)当陈述部分有never,seldom, hardly,few,little,barely, scarcely, nothing 等否定意义的词时,后面的反意疑问句则为肯定形式: There are few apples in the basket, are there? He can hardly swim, can he? They seldom come late, do they? (2)当陈述部分含有否定意思的词是unhappy,dislike,unfriendly等含有否定词缀的派生词,也就是有un-前缀、-less后缀等含有词缀而意思否定的词,当做肯定句处理,疑问部分要用否定形式。如: He looks unhappy,doesn't he?他看上去不高兴,不是吗? The girl dislikes history,doesn't she?这女孩不喜欢历史,不是吗?有less,fewer等词视为肯定词,疑问部分用否定形式。如: There will be less pollution, won't there?
表示主语主观意愿的词
含有think, believe, suppose, imagine, expect等动词后接宾语从句构成的主从复合句在构成反意疑问句时,视情况不同有两种不同的构成方式。 (1.)当主句的主语为第一人称时,其后的简短问句应与从句相一致。例如: I expect our English teacher will be back this weekend, won't she/he? We suppose you have finished the project, haven't you? 值得注意的是,当这些动词后接的宾语从句的否定转移到主句时,其仍属否定句,故其后的简短问句应用肯定式,而非否定式。例如: I don't believe that he can translate this book, can he? Wedon't imagine the twins have arrived, have they? 此类句子的回答同"前否后肯"型反意疑问句一样,如上述后一个句子,若双胞胎已经到了,则回答为"Yes, they have.";若尚未到达,使用"No, they haven't."。 (2).当主句的主语为第二、三人称时,其后的简短问句则应与主句相一致(此时,否定只看主句,与从句无关...)。例如: Your sister supposes she needs no help, doesn't she? You thought they could have completed the project, didn't you? They don't believe she's an engineer, do they? She doesn't expect that we are coming so soon, does she? (3)但如果主句的时态是过去时等等,疑问句应和主句的人称时态保持一致。
had better或have
陈述部分有had better,或其中的have表示完成时态时,疑问句应用hadn’t等开头: You’d better get up early, hadn’t you? 其他情况句中有have时疑问句应用don't等开头 如have表示“有”的时候,有两种形式:(have 表示有 可用do或 have来改写) -He has two sisters,doesn't he? =He has two sisters,hasn't he? -He doesn't have any sisters,does he?
祈使句
当陈述部分是祈使句时,疑问句要根据语气来表达,分三种情况: 1)一般情况下用will you 或 won't you。 e.g. Give me a hand,will you? Leave all the things as they are,won't you? 2)以Let's开头的祈使句,前肯后可肯可否,前否后只可,疑问句用shall we;以Let us或Let me开头的祈使句,问句用will you。 e.g. Let's go out for a walk, shan't we? Let us go out for a walk, will you? Let me help you,will you? 3)当陈述句是否定的祈使句时,问句可用will you 或 can you 。 e.g. Don't make much noise,will/can you?
There be句型
There be 句型中,反义疑问部分必须为be 动词 + there There are some apples in the basket, aren't there? There isn't any milk left, is there?
must
.当陈述部分有情态动词must,问句有4种情况: (1)mustn't表示“禁止,不可,不必”时,附加问句通常要用must. You mustn't stop your car here,must you? 你不能把车停在这地方,知道吗? (2)must表示“有必要”时,附加问句通常要用needn't. They must finish the work today,needn't they? 他们今天要完成这项工作,是吗? (3)当must用来表示对现在的情况进行推测时,问句通常要根据must后面的动词采用相应的形式。 He must be good at English,isn't he? 他英语一定学得很好,是吗? (4)当must+have done表示对过去的情况进行推测(一般句中有明确的过去时间状语),问句要根据陈述部分谓语的情况用“didn't+主语”或“wasn't/weren't+主语”;如果强调动作的完成(一般没有明确的过去时间状语),问句要用“haven't/hasn't+主语”。 She must have read the novel last week,didn't she? 她上星期一定读了这本小说,是吗? You must have told her about it,haven't you? 你一定把这事告诉她了,是吗?
反意疑问句的回答用yes, no, 但是 ,回答翻译相反,回答要按事实。如: (1)They work hard,don’t they?他们努力工作,不是吗? Yes, they do.对,他们工作努力。/No, they don't.不,他们工作不努力 (2)They don’t work hard, do they? 他们不太努力工作,是吗? Yes, they do. 不,他们工作努力。/No, they don't. 对, 他们工作不努力