1、*1*情态动词一、考点聚焦1、 情态动词的基本用法(1)can、be able to 和 couldcan 和 be able to 都表示能力，意思上没多大区别。但 can 只有现在和过去时，而 be able to 则有更多的形式。但当成功地完成某一具体动作时，通常不用 could 而用 was/were able to 来表示。这时 was/were able to 相当于 managed to，表示经过一番努力，终于能够完成某事。如：Can you use chopsticks?The wounded man still was able to get to the village a
2、nd was saved in the end.can 和 couldcan 和 could 都可以表示能力、技能、许可、建议或请求和可能性。但比较委婉客气地提出问题或陈述看法，一般用 could，回答时则用 can。如：Could you help me carry the bag?Can I help you?(2)may/mightmay/might 表示可能，但 may 比 might 可能性大。如：-Why isnt he in class?He may be sick.(生病的可能性较大)He might be sick.(生病的可能性较小)may/might 表示“允许” ，ma
3、y 用于现在时或将来时，might 常用在间接引语中表过去时，但 might 也可用于现在时间，表示比较委婉的语气，回答用 may。如：He says we may leave.He said we might leave.may / might 表示建议或请求，但 might 比 may 更客气，意思更肯定而无过去时态的含义。Yes, you can / may.May / Might I use your bike? No, you mustnt（3）mustmust 表示必须，应该，没有时态变化。如：You must do everything as I do.must 表示肯定的推测。
4、如：The light is still on, so he must be at home.mustnt 表示禁止做某事。如：You mustnt smoke in the office.（4）have tohave to 表示“必须、不得不” ，是由于某种外界（客观）原因而“必须” ， “不得不”做某事，也可表示经常的或习惯性的事“必须”做。have to 的否定形式表示不必。have to 可用于多种时态中。如：*2*You will have to clean your own boots when you join the army.I have to be at my office
5、 every evening.（5）should / ought toshould 和 ought to 表示应当、应该，前者比后者语气轻。如：You should / ought to work hard.should / ought to work hard.Since she is not here, whe should / ought to be in the classroom.should / ought to 的否定形式表示禁止之意。如：Children shouldnt smoke.should 可表示陈述意见，推出建议或请求；而 ought to 可以表示劝告之意。如：Yo
6、u ought to respect your parents.He suggested that they should leave at once.（6）will / wouldwill 用于各种人称表示“意志” 、 “意愿”或“决心”等，否定式 wont + 动词。如：I will tell you all about it.Tom wont do such a thing.will 用于疑问句中，常用在第二称时表示说话人向对方提出“请求”或“询问”如：Will you please tell her the news when you see her?will 表示习惯性的动作，有“总
7、是” 、 “惯于”的含义。如：Fish will die out of water.would 表示客气的请求、建议或意愿。如：Would you please be quiet?Would you like coffee?would 表示过去反复发生的动作。如：When I passed my school I would see my teachers who taught me 5 years ago.（7）needneed 作“必要”讲，既可作情态动词，也可作实义动词。作实义动词时后面的动词不定式要带 to，其变化与一般动词相同。如：I need to think it over.Ne
8、ed you go now? Yes, I must./No, I neednt （8）daredare 表示“敢”的意思。作为情态动词时，主要用在疑问句和否定句中。dare 若作实义动词，后面可带 to 的不定式，此时 to 也可以省略。dare 与 need 的用法相似。如：How dare you say that?She doesnt date(to)ask her father.（9）used toused to 表示过去常常发生的动作或存在的习惯，但现在已不复存在了。如：He used to smoke.*3*（10）shallshall 作为情态动词用于第二、三人称，表示说话人的
9、意愿，有“命令” 、 “警告、威胁、强制”和“允许”等意思。如：We shall do as our teacher says.You shall have the book as soon as I finish it.在疑问句中，shall 用于征求对方的意见或请求指示，常用于第一、第三人称。如：Where shall he wait for us?Shall we go out for a walk?2、情态动词表示推测或判断的用法下表即是表示推测的情态动词使用的场合：例如：It must have rained last night.She may not be at home. =
10、It is possible that she is not at home.She cant be at home. = It is impossible that she is at home.They should be there right now.3、情态动词在虚拟语气中的用法情态动词用于虚拟语气中表示责备的感情色彩，用法如下：（1）should have done 表示“本来应该做某事而实际上未做 ”，而 shouldnt have done则表示“本不应该做某事而实际上做了” 。如：You should have told me about it earlier.You sho
11、uldnt have said such words to your parents.（2）ought to have done 也表示 “本应该”而 ought not to have done 则意为“本不应该” 。如：You ought to have told me about it earlier.You ought not to have said such words to your parents.（3）neednt have done 表示“本无必要做某事而实际上做了” 。如：情态动词 对现在和未来的推测 对过去的推测 使 用 场 合must must + 动词原形 must
12、 have done 肯定句may / might may / might + 动词原形May / might have done 肯定句、否定句can /could can / could doCan / could have done否定句、疑问名（could 可用于肯定句）should用来表示一种估计的情况“按理会/估计会”should do/beshould have done 肯定句、否定句、疑问句*4*You neednt have walked so quickly since time was enough.（4）could have done 表示“ 本来有可能而事实上未做到 ”。如：I could have come on time, but my car broke on the way.
