内容正文:
初中英语语法精讲精练 chapter 8 情态动词
情态动词不能表示正在发生或已经发生的事情,只表示期待或估计某事的发生。除 ought 和have 外,后面只能接不带 to 的不定式。情态动词没有人称、数的变化,即情态动词 第三人称单数不加-s 。情态动词没有非谓语形式,即没有不定式,分词等形式。
一、情态动词用法
难点精讲
1.must
(1)must 表示自己的主观看法或要求别人必须做某事。意为“必须”、“应该”,如:We must learn English hard. 我们必须努力学习英语。
(2)must 表示推测,意为“准是、一定”,一般指可能性很大。如:
The woman must be Li Lei's mother. 那个妇女一定是李雷的母亲。
(3)must 表示推测时,其否定式不用mustn't, 而用can't 。如 :
The door is closed.He can't be at home. 门关着,他不可能在家。
(4)mustn't 表示“不可以”、“禁止”。如:
You mustn't play on the road.你不可以在路上玩。
(5)以must 开头的疑问句,肯定回答用must, 否定回答用needn't, 意为“不必”。
(6)must 与 have to的区别:must 表示主观的看法,have to 表示客观的需要。must 只有一 种形式,而have to 有多种形式。第三人称单数现在时用has to, 过去式用had to, 将 来时态用will have to。
2.need
need 既可用作情态动词,亦可用作实义动词。用作情态动词时,它只有一种形式,后跟不 带 to 的动词不定式,只用于否定句和疑问句。用作实义动词时,它有动词的全部形式,即 现在时单数第三人称needs, 现在分词needing 以及过去式和过去分词needed, 后跟带 to 的不定式,可用于一切句式。如:
3. 比 较can 和 be able to
(1)can 、could 表示“能力”;“可能”(过去时用could), 只用于现在式和过去式(could)。
be able to 可以用于各种时态。如:
They will be able to tell you the news soon.他很快就能告诉你消息了。
(2)以下情况下只用be able to:
①位于助动词后。
②情态动词后。
③表示过去某时刻动作时。
④用于句首表示条件。
⑤表示成功地做了某事时,只能用was/were able to,不能用could。
He was able to flee Europe before the war broke out.
=He managed to flee Europe before the war broke out. 战争爆发前他得以逃离欧洲。
「 注意』could 不表示时态,其特殊用法有:
1)提出委婉的请求,(注意在回答中不可用could)。
—Could you lend me your bike? 能把你的自行车借我用一下吗?
—Yes,you can./No,you can't. 行。/不行。
2)在否定,疑问句中表示推测或怀疑。
He couldn't be a bad man.他不大可能是坏人。
4. 比较 may 和 might
(1)表示允许或请求;表示没有把握的推测;may 放在句首,表示祝愿。
May you succeed! 祝你成功!
He might be at home.他可能在家。
「注意 ]might 表示推测时,用might 代 替 may 时,有时语气更委婉、更不肯定,这时 might 不表 示时态。
(2)成语搭配: may/might as well,后面接不带 to 的不定式,意为“不妨”。
If that is the case,we may as well try.如果那是个原因的话,我们不妨试试。
5. 比较 have to 和 must
(1)两词都是“必须”的意思,have to 表示客观的需要,must 表示说话人主观上的看法,即 主观上的必要。如:
My mother was ill,so I had to look after her at home.
我妈妈病了,我必须在家照顾她。 (客观上需要做这件事)
He said that they must work hard. 他说他们必须努力工作。 (主观上要做这件事)
(2)have to 有人称、数、时态的变化,而must 只有一种形式。但must 可用于间接引语中表 示过去的必要或义务。
He had to look after his sister yesterday. 他昨天必须照顾他妹妹。
(3)在否定结构中: don't have to 表示“不必”;mustn't 表示“禁止”。如:
You don't have to tell him about it. 你不一定要把此事告诉他。
You mustn't tell him about it. 你一定不要把这件事告诉他。
6.表示推测的用法
can,could,may,might,must 皆可表示推测,其用法如下:
(1)情态动词+动词原形。
表示对现在或将来的情况的推测,此时动词通常为系动词。
I don't know where she is,she may be in Shenzhen.
我不知道她在哪里,可能在深圳吧。
(2)情态动词+动词现在进行时。
表示对现在或将来正在进行的情况进行推测。
At this moment,our teacher must be correcting our exam papers.
这时,我们的老师想必在批改试卷。
(3)情态动词+动词完成时。
表示对过去情况的推测。
We would have finished this work by the end of next December.
明年十二月底前我们很可能已完成这项工作了。
The road is wet.It must have rained last night.
地是湿的,昨天晚上一定下雨了。
(4)情态动词+动词的现在完成进行时。
表示对过去正在发生事情的推测。
Your mother must have been looking for you. 你妈妈一定一直在找你。
(5)推测的否定形式,疑问形式用can't,couldn't表示。
Mike can't have found his car,for he came to work by bus this morning.
迈克一定还没有找回他的车,因为早上他是坐公共汽车来上班的。
『注意」could,might 表示推测时不表示时态,其推测的程度不如 can,may。
7.should 和 ought to
should 和 ought to 都为“应该”的意思,可用于各种人称。
—Ought he to go? 他应该去吗?
—Yes.I think he ought to. 是的,我想他应该去。
表示要求,命令时,语气由 should(应该)、had better(最好)、must (必 须) 渐强。
8.had better
had better表示“最好”,相当于一个助动词,它只有一种形式,它后面要跟动词原形。 It is pretty cold.You'd better put on my coat. 天很冷,你最好把我的大衣穿上。
You'd better not play with the dirty dog. 你最好不要跟这只脏狗玩耍。
9.would rather
would rather 表示“宁愿”,would rather...than…宁愿……而不愿。如:
I would rather stay here than go home.=I would stay here rather than go home. 我宁愿待在家里也不愿回家。
10.will 和 would
(1)would like;Would like to do =want to“想要”,为固定搭配。 Would you like to go with me? 你想跟我一起吗?
(2)Will you..?Would you like.…? 表示肯定含义的请求劝说时,疑问句中一般用some, 而不是any。
Would you like some cake? 你要些蛋糕吗?
(3)否定结构中用will, 一般不用would,won't you 是一种委婉语气。
Won't you sit down? 为什么不坐下?
11.情态动词的回答方式
问 句 肯定回答 否定回答
Need you.…? Yes,I must. No,I needn't
Must you.…? I don't have to.
12.带 to的情态动词
带 to 的情态动词有四个:ought to,have to,used to,be to,它们的疑问、否定形式应予以
「注意』
Do they have to pay their bill before the end of the month? 他们必须在月底前付账吗? She didn't use to play tennis before she was fourteen.她14岁前不是常常打乒乓球的。
You ought not to have told her all about it.你应该别把所有有关那件事的事告诉她。
Ought he to see a doctor at once? 他应该马上去看医生吗?
ought to 本身作为情态动词使用。其他的词作为实义动词使用,变疑问,否定时,须有do 等助动词协助。
13. 比 较 need 和 dare
这两词既可做实义动词用,又可做情态动词用。作为情态动词,两者都只能用于疑问句,否定句和条件句。 need 作实义动词时后面的不定式必须带 to, 而 dare 作实义动词用时,后面的 to时常可以被省略。
(1)实义动词: need (需要,要求) need +n./to do sth.
(2)情态动词: need, 只用原形 need 后 加 do, 否定形式为need not。
Need you go yet? 你还需要走吗?
Yes,I must./No,I needn't. 是的,我必须要走。/不,我不是非得走。
(3)need 的被动含义:need,want,require,worth(adj.) 后面接 doing 也可以表示被动: need doing =need to be done
A man can.fail many times,but he isn't a failure until he begins to blame somebody else.
一个人可以失败很多次,但是只要他没有开始责怪旁人,他还不是一个失败者。
The people who get on in this world are the people who get up and look for circumstances they want,and if they cannot find them,make them.
在这个世界上取得成就的人,都努力去寻找他们想要的机会,如果找不到机会, 他们便自己创造机会。
一 讲 一 练
1.Peter come with us tonight,but he isn't very sure yet.
A.must B.may C.can D.will
「析』表可能性只能用 may, 此句意可从后半句推出。故选 B。
2.—Shall we go skating or stay at home?
—Which do?
A.do you rather B.would you rather
C.will you rather D.should you rather
『析』本题考查情态动词 rather 的用法,would rather +do sth 意为“宁愿”,本题为疑问句, would 提前,故选 B。
3.——Could I borrow your dictionary?
—Yes,of course,you
A.might B.will C.can D.should
『析』could表示委婉的语气,并不为时态。答语中of course,表示肯定的语气,允许某人做某 事时,用can 和 may 来表达,不能用could 或 might 。复 习 :will 与 you 连用,用来提出要求或 下命令。 should 与 you 连用,用来提出劝告。故选C。
4.—Shall I tell John about it?
—No,you .I've told him already.
A.needn't B.wouldn't C.mustn't D.shouldn't
『析』needn't 不必,不用。wouldn't 将不,不会的。mustn't 禁止、不能。shouldn't 不应该。本题 为不需要,不必的意思,应用needn't 。 故 选A。
5.—Don't forget to come to my birthday party tomorrow.
A.I don't B.I won't C.I can't D.I haven't
「析』will 既可当作情态动词,表请求、建议、也可作为实义动词表“意愿、意志、决心”,本题 表示决心,故选 B。
6.—Listen!Helen is singing in the next room.
—It be Helen.She has gone to Beijing.
A.can't B.mustn't C.may D.should
「析』can't 表示不可能,肯定不是,因为Helen 去了北京,不可能在隔壁唱歌,故选A。
7.—May I put my bike here?
—No,you .You should put it over there.
A.couldn't B.needn't C.mustn't D.won't
『析』情态动词 may 为开头的问句,否定回答应用mustn't, 故 选C。
8.Tom ought not to me your secret,but he meant no harm.
A.have told B.tell C.be telling D.having told
『析』由于后句为过去时,告诉秘密的动作又发生在其前因,此地应用过去完成时,但它在情态动词ought to后,所以用have。故选A。
A组:选择最佳答案填空
1.—Must I hand in the exercise-book now?
—No,you
A.mustn't B.can't C.needn't D.may not
2.You talk so loud in the library.
A.needn't B.mustn't C.can't D.not
3.— I come here tonight?
—No,you needn't.
A.May B.Can C.Must D.Shall
4.—You must be here at six tomorrow morning.
—Sorry.I be here so early.
A.need B.may C.must D.can't
5.—Can you answer this question in English?
—No,I
A.needn't B.may not C.can't D.mustn't
6.Don't be late.You be there on time
A.must B.can C.may D.needn't
7.— I use your dictionary?
—-Certainly,here you are.
A.Must B.May C.Need D.Shall
8. you swim?No,I
A.Can;can B.Must;can't C.Can;can't D.May;can't
9.“What for you?”said the waiter.
A.I can do B.can I do C.I may do D.may I do
10.We hardly hear you.Please speak up a bit.
A.can B.can't C.may not D.must
11.The light is poor.I see the words on the blackboard.
A.mustn't B.don't C.can't D.needn't
12.It's a fine day today.You take a raincoat with you.
A.can't B.mustn't C.needn't D.can
13.You play football in the street.It's dangerous.
A.can B.must C.needn't D.mustn't
14.I've looked for my pen everywhere,but I find it.
A.couldn't B.can't C.mustn't D.didn't
15.Excuse me, I have a look at that book?
A.will B.do C.may D.would
答案:1~5 CBCDC 6~10 ABCBA 11~15 CCDBC
halcyon days太平盛世
希腊神话中,风神的女儿海尔赛妮(Halcyone)和晨星的儿子刻宇克斯
(Ceyx)是一对恩爱夫妻。有一趟,刻宇克斯出海溺死了,天后怜悯整天惦记着 丈夫的海尔赛妮,就让刻宇克斯的尸体漂到他家附近岸边。海尔赛妮看见了,哭 着跳进海里,忽然变成一只翠鸟(halcyon),她丈夫也同时化为翠鸟和妻子比翼 双飞。每年冬天,他们会在海上浮巢里孵卵。风神由于怜悯女儿,翠鸟孵卵期间 从不兴风作浪。所以,人们现在就用halcyon days来说冬至前后两个星期气候 稳定的日子,或比喻宁静幸福的年代。
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