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专四情态助动词考点

时间:2020-08-13 18:52:34 专四 我要投稿

2018专四情态助动词考点

  英语专业四级语法是2018英语专业四级考试考生复习初期首先要打好基础的部分,因为英语语法贯穿于整个英语专四考试中,尤其是应用于专四完形填空及专四语言知识题型,下面应届毕业生考试网小编为大家介绍的2018专四情态助动词考点,欢迎阅读。

  ❖ 主要情态助动词的用法(can/could, may/might, will/would, shall, should, must, need, dare)

  ❖ 情态动词+have+过去分词

  1) can和could的用法

  1. 表示能力,如: Can you finish this work tonight?

  2. 理论上的可能性,但未必马上发生。“有时候会”

  Man cannot live without air. My sister can be really stubborn.

  3. 表示请求和允许。 — Can I go now? — Yes, you can.

  注意:①could也可表示请求,语气委婉,主要用于疑问句,不可用于肯定句,答语应用can(即could不能用于现在时态的简略答语中)。如: Could I come to see you tomorrow?

  Yes, you can. (否定答语可用No, I'm afraid not.) ②can表示能力时,还可用be able to代替。如: I'll not be able to come this afternoon.

  4. can表示惊异、怀疑、不相信的态度,是一种推测.(主要用在否定句、疑问句或惊叹句) Could既可用于肯定句又可用于否定句、疑问句

  Can this be true? How can you be so careless! This cannot be done by him.

  5. “can + have done” 用于否定句、疑问句表示对过去发生的行为怀疑或不肯定。 “could + have done”可用于各种句型。如: He cannot have been to that town. Can he have got the book? 6. 特殊句式

  (1) can not / can never too…或cannot…enough “再……也不过分,越……越好” One can’t be too careful. = One can’t be careful enough.

  (2)can’t help doing / can’t help but do禁不住,不由得 (3)Can’t help (to) do 不能帮助做某事 (4) can’t/couldn’t + 比较级=最高级

  2) may和might的用法 1. 表示许可。 表示请求、允许时,might比may的语气更委婉一些,否定回答时要用mustn't表示“不可以”、“禁止”、“阻止”之意。如: You may drive the car.

  — Might I use your pen? — No, you mustn't.

  用May I ... 征询对方许可在文体上比较正式,在口气上比较客气。在日常口语中,用Can I ... 征询对方意见在现代口语中更为常见。

  肯定回答用Yes, you may./Yes, please./Certainly./Sure, go ahead. 否定回答用No, you mustn’t./No, you’d better not.

  2. 用于祈使句中表示祝愿。May+主语+动词原形

  如: May you succeed!

  3. 表示推测,一般不用于疑问句。might的可能性比may小。 He may be very busy now.

  4. “may(might) + have done”表示对过去发生的行为的推测。如: He may not have finished the work.

  5. may / might as well +动词原形 “不妨,不如” You may / might as well go to see a doctor.

  3) must和have to的用法 1. 表示必须、必要。如: You must come in time. 回答must引出的问句时,如果是否定的回答,不能用mustn't,而要用needn't或don't have to。 — Must we hand in our exercise books today? — Yes, you must. (No, you don’t have to.)

  2. must表示命令或强制,用于否定句的mustn't表示说话人不许或禁止(某人做某事)。例如:You must do as you are told. 你必须遵嘱行事。

  You mustn't move any of the papers on my desk. 你不许动我办公桌上的任何文件。 —May I borrow this book? 我可以借这本书吗? —No,you mustn't. 不,不可以。

  3. must表示“偏要”, “非要”

  Must you make so much noise? 你偏要弄出那么多噪音吗? Of course,after I gave her advice, she must go and do the opposite. 当然,在我劝了她以后,她非要做相反的事不可。

  4. must表示推测,只用于肯定句。它的否定或疑问式用can /could代替must。 This must be your pen.

  5. “must + have + done”的结构常用在肯定句中,表示对过去发生的行为的推测。它的否定或疑问式用can/could代替must。 He must have been to Shanghai. 含Must的反义疑问句:

  A.must表示“应该”,其疑问部分用mustn't(不应该),如:

  You must work hard next term, mustn't you ? 下学期你应该努力学习,对吗? B.must表示“必须”,其疑问部分用needn't(不必),如:

  They must finish the work today, needn’t they? 他们今天必须要完成这项工作,是吗? C.陈述部分含情态动词mustn't,表示禁止时,疑问部分就可以用must或may,如: You mustn’t stop your car here, must you? (may we?)你不能把车停在这地方,知道吗? D.must表示推测 ,其疑问部分必须与must 后面的主要动词相呼应。如: ①对现在动作或存在的情况的推测 :

  You must know the answer to the exercise, don't you? 你一定知道这项练习的答案,是不是? That must be your bed, isn't it? 那一定是你的`床,是吗? ②对过去发生的动作或存在的情况的推测:

  (一)句中陈述部分没有表示过去的时间状语,这时疑问部分中的动词就用 现在完成时。(haven’t / hasn’t + 主语)

  You must have told her about it, haven’t you? 你一定把这事告诉她了,是吗? (二)陈述部分有表示过去的时间状语,疑问部分的动词就用 一般过去时。(didn’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了,是吗? 6. have to的含义与must相似,两者往往可以互换使用,但have to有各种形式,随have的变化而定。must与have to有下列几点不同:

  ① must表示的是说话人的主观看法,而have to则往往强调客观需要。如: The play is not interesting. I really must go now. I had to work when I was your age.

  ② 二者的否定意义不大相同。如:

  You mustn't go. 你可不要去。 You don't have to go. 你不必去。 ③ 询问对方的意愿时应用must。如: Must I clean all the room?

  4) dare和need的用法

  1. need表示“需要”或“必须”,作情态动词时,仅用于否定句或疑问句中,在肯定句中一般用must, have to, ought to,或should代替。如: You needn’t come so early.

  — Need I finish the work today? — Yes, you must.

  注意:needn't +完成式“表示本来不必做而实际上做了某事”。如: You needn't have waited for me.

  2. Dare作情态动词时,主要用于疑问句、否定句和条件从句中,一般不用在肯定句中。有过去时dared。如:How dare you say I'm unfair. He daren't speak English before such a crowd, dare he?

  3. Dare和need可作实义动词,用于各种句型,有时态、人称和数的变化,所不同的是,作实义动词时,在肯定句中,dare后面通常接带to的不定式,在否定和疑问句中,dare后面可接带to或不带to的不定式。如:

  I dare to swim across this river. He does not dare (to) answer. Don't you dare (to) touch it! He needs to finish it this evening.

  5) shall和should的用法

  Shall(1)用于第一人称的陈述句,表示将来。如: I shall come tomorrow.

  (2). Shall用于第一、第三人称疑问句中,表示说话人征求对方的意见或向对方请示。如: Shall we begin our lesson?

  When shall he be able to leave the hospital?

  (3). Shall用于第二、第三人称,表示说话人给对方命令、警告、允诺或威胁。如: You shall fail if you don't work harder. (警告)