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(共20张PPT)
聚焦语法
第10讲　情态动词与虚拟语气
思维导图
情态动词
考点精讲
Ⅰ.常见的情态动词
情态动词 词义 否定式 缩略否定式
can/could 能；能够；可能 can/could not can't/couldn't
may/might 可以；也许 may/might not mayn't/mightn't
must 必须；一定 must not mustn't
should 应该 should not shouldn't
ought to 应当 ought not to oughtn't to
shall 可；必将 shall not shan't
will/would 愿意；决心 will/would not won't/wouldn't
need 需要 need not needn't
dare 敢 dare not daren't
Ⅱ.情态动词的用法
情态动词 用法 例句
can/could ①can表示现在具有某种能力或技能，意为“能，会” ②could表示过去一般性能力 ③表示请求允许。在一般疑问句中，could 可代替can, 但语气更委婉，答语要用can ④用于固定句型中：can't…too/enough(无论……也不为过)；can't help doing sth.(禁不住做某事)；can't help but do sth.(不得不做某事) ；can not/could not but do sth.(不得不做某事) ①Tom can speak English.
②Tom could sing English songs when he was 6.
③—Can/Could you help me
—Yes, I can.
④I can't praise him too much.
I couldn't but give it up.
情态动词 用法 例句
may/might ①may表示请求或允许，“可以”。might表示请求时语气更为委婉。might是may的过去式，常用于间接引语 ②may、might表示推测，用于肯定句，“可能”；用于否定句，may not“可能不”；表“不可能”，用can't ③may表祝愿，其结构为：May＋主语＋do ④固定句型：may/might as well do(不妨，还是做……为好)；may/might well do＝be very likely to do(很有可能做……) ①May I help you
She said I might visit her at any time.
②This coat may be Tom's.
This coat may not be Tom's.
This coat can't be Tom's.
③May you succeed!
④So you might as well go there and have a look at it.
情态动词 用法 例句
must ①表必要性，“必须”，否定式为needn't/don't have to ②mustn't 表禁止，“不准” ③表坚持，“偏要，非要” ④表推断，用于肯定句，“一定，准是” ①—Must I come before 8:00 a. m.
—Yes, you must./No, you needn't./No, you don't have to.
②You mustn't smoke here.
③Must you say like this
④You must be tired after such a long walk.
情态动词 用法 例句
shall ①表示征求对方意见或请求，用于第一、三人称的疑问句中 ②用于第二、三人称的陈述句中，表示说话者的意志，用来表示说话者给对方的命令、警告、允诺等。在条约、规定、法令等文件中表示义务或规定，“应该，必须” ①Shall I go now
②You shall have a bicycle for your birthday.
Every student shall obey these rules.
情态动词 用法 例句
should ①相当于ought to，“应该”，表义务上的应该，也可表推测上的“按说应该” ②“竟然”，表说话人的惊讶、难以置信等情绪 ③用作shall 的过去式，表示打算或期望做的事 ①You should turn in your homework on time.
He should be arrive by now.
②It's strange that he should fail the exam.
③I knew that we should have a meeting the next day.
will/would ①用于各种人称，表示主语的意愿和意志 ②用于第二人称的一般疑问句，表请求 ③will用来叙述目前的习惯；would表示过去的习惯 ①He will come to help you.
②Will/Would you go with me
③He would stay up late into the night.
情态动词 用法 例句
need/dare ①need和dare用作情态动词时，主要用于否定句、疑问句和条件状语从句中，没有人称和数的变化，后接动词要用动词原形 ②need和dare用作实义动词时，后接动词要用不定式，有人称和数的变化，在肯定句、否定句和疑问句中都可以使用，并且need作实义动词“需要”解释，后接动名词相当于不定式的被动式 ①He needn't do it.
②He doesn't need to do it.
Ⅲ.“情态动词＋现在完成时”的用法
形式 含义 例句
can/could have done 本来能够做；过去可能会做 Can he have finished the work
must have done 推测某事必定已经发生 It must have rained last night, for the road is so muddy.
may/might have done 也许/或许已经做了(might语气更弱) You may have narrowly missed her on your way here.
should/ought to have done 本应该做而实际上没做 You should/ought to have finished the exercise more carefully.
needn't have done 本不必做而做了 There was plenty of time.She needn't have hurried.
虚拟语气
思维导图
考点精讲
Ⅰ.虚拟语气的概念：表示说话人所说的不是事实，而是一种愿望、假设或推测。
虚拟条件 从句谓语形式 主句谓语形式 例句
与过去 事实相反 had＋done should/would/could/might＋have＋done If you had studied hard before, you would have passed the exam.
与现在 事实相反 did(be动词用were) should/would/could/might＋do If we left now, we would arrive in good time.
If there were no gravity, we should not be able to walk.
与将来 事实相反 一般过去时/ should/were to＋do should/would/could/might＋do If you came tomorrow, we would meet you at the airport.
If he should go away, I would do it in a different way.
Ⅱ.虚拟语气用于条件状语从句时，主句与从句的动词形式
Ⅲ.三种特殊的虚拟条件从句
事项 注意点 例句
错综时间条件句 当条件状语从句表示的行为和主语表示的行为发生的时间不一致时，动词的形式要根据表示的时间来调整 If you had followed my advice, you would be better now.
倒装句 条件状语中可省略if，把were、had、should提到句首，变成倒装句式 If I were at school again, I would study harder.
→Were I at school again, I would study harder.
含蓄条件句 用介词短语代替条件状语从句。常用的介词有with、without、but for I wouldn't have won the prize without my teacher's help.
Ⅳ.虚拟语气在其他从句中的运用
类别 解说 例句
在主语 从句中 在“it's＋形容词/过去分词＋that…”这类句型中，主语从句中的谓语动词形式常用“(should＋)动词原形”结构。另外，表示“提议，要求，命令”等动词的过去分词也可以这样用。常用句型： it is necessary/important/strange/natural/ essential/…that… it is suggested/requested/desired/proposed/ demanded/…that… It is necessary that we (should) master at least one foreign language.
类别 解说 例句
在宾语 从句中 ①用于wish后的宾语从句中，表示说话人认为不可能实现的愿望： 表示对现在情况的虚拟：从句动词用过去时或过去进行时(be动词一般用were) 表示对过去情况的虚拟：从句动词常用“had＋过去分词” 表示对将来的主观愿望：从句谓语动词形式为“should/might/would/could＋动词原形” ②在suggest、demand、order、propose、insist、command、request、desire等动词后的宾语从句中，谓语动词用“(should＋)动词原形”，表示“建议，要求，命令”等 ③would rather后面的宾语从句常用虚拟语气。在这种结构中，从句中的谓语动词通常用过去时表示对现在和将来的虚拟，用过去完成时表示对过去的虚拟 常用动词的巧记口诀：一坚持(insist)，二命令(order、command)，三建议(advise、suggest、propose)，四要求(demand、require、request、desire) ★当insist意为“坚决认为，坚持说”，suggest意为“表明，暗含，暗示”时，宾语从句一般不用虚拟语气 ①I wish I knew what to do!
②The policeman insisted that she (should) have a look.
③I would rather you stayed at home.
类别 解说 例句
在状语 从句中 ①as if/as though引导的从句所表示的内容往往不是事实，常用虚拟语气，其形式与wish后宾语从句中的谓语动词相同 ②在so that、in order that引导的目的状语从句中，谓语动词多用“may/might＋动词原形”或“can/could＋动词原形” ③在whatever、whoever、no matter what等引导的让步状语从句中，谓语动词多用“may＋动词原形” ①He talks as if he knew everything.
②I live so that others may live better.
③I won't let you in whoever you may be.
类别 解说 例句
在表语 从句和 同位语 从句中 在表示“意愿，要求，命令，建议”等名词后的表语从句或同位语从句中，谓语动词用“(should＋)动词原形”，这类名词有idea、proposal、suggestion、advice、order、plan、decision、desire、requirement等 She put forward a suggestion that we (should) go for an outing this Sunday.
类别 解说 例句
在定语 从句中 句型it is (high/about) time (that)…中，从句用虚拟语气，其谓语动词的形式为过去式或“should＋动词原形”，should不可省略，意思是“是该做……的时候了” In my opinion, it is about time we had/should have new computers.
表示 惊叹 if only引导的感叹句使用虚拟语气，谓语动词用一般过去时表示对现在事实的虚拟，用过去完成时表示对过去事实的虚拟，意为“但愿，要是……多好” If only I were ten years younger.

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