情态动词表推测时can,could与must,might有何区别？
情态动词表推测时can,could与must,might有何区别？
请详细地讲解
情态动词 (Model Verbs) 又称为情态助动词 (Model Auxil-iaries)。英语中助动词主要有两类：一是基本助动词，如have, do, be；二是情态助动词，如may, must, need等。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。在大学英语四、六级考试中，情态动词部分重点测试以下内容：
&&& （1）情态动词+行为动词完成式
&&& （2）情态动词+行为动词进行式
&&& （3）情态动词+行为动词完成进行式
&&& （4）某些情态动词的特殊用法
&&& 一、情态动词+行为动词完成式
&&& 情态动词+行为动词完成式即“情态动词+ have + v-ed分词”，表示对过去行为或动作进行推测、评论或判断。
&&& 1. must have v-ed
&&& must have v-ed 表示推测过去某事“一定”发生了。其否定形式为：can’t / couldn’t have v-ed, 表示过去不可能发生某事。例如：
&&& 1）Since the ditch is full of water, it must have rained last night.
&&& 2）You couldn’t have met my grandmother. She died before you were born.
&&& 2. could have v-ed
&&& could have v-ed 表示推测过去某动作“很可能”发生了。例如：
&&& 1）“The dictionary has disappeared. Who could have taken it?”
&&& 2）“Tom could have taken it. He was alone yesterday.”
&&& 3.may / might have v-ed
&& &may / might have v-ed 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.
&&& 4. ought to / should have v-ed 和 ought not to / shouldn’t have v-ed
&&& ought to / should have v-ed 和 ought not to / shouldn’t have v-ed 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 make fun of him. He is not the one you laugh at but learn from.
&&& 5. needn’t have v-ed
&&& needn’t have v-ed 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’ 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+行为动词进行式
&&& 情态动词+行为动词进行式（即情态动词+ be + v-ing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+行为动词完成进行式
&&& 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，对此，可参见表1.need 作情态动词时，后面跟不带to 的动词不定式，即 “need to”。通常用在疑问句和否定句中，表示询问是否有“必要”，其否定形式为needn’t，表示“不必”；疑问形式为 Need … do? 极少用于肯定句。例如：
&&& 1）I don’t think we need turn the light on at that time.
&&& 2）Need you ride a bike to school?
&&& 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表1。
&&& 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表2。
&&& 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。
时态&&&&& 情态动词need&&&&&&&&&&&&&& 实义动词 need
&现&&&& You need (not) do&&&&& You (don’t) need to do&&&&&&&&&&&
&时&&&& He need (not) do&&&&&& He needs (doesn’t need) to do
&过&&&&&&&&&&&&&&&&&&&&&&&&&&& You needed (didn’t need) to do&
&时&&&&&&&&&&&&&&&&&&&&&&&&&&& He needed (didn’t need) to do
&将&&& You need (not) do&&&&&& You will (not) need to do
&时&&& He need (not) do&&&&&&& He will (not) need to do
&句型&&& 时态&&&&&&&&&&&&&&&&&&&& 动词&&
&&&&&&&&&&&&&&&&& 情态动词dare&&&&&&&&&& 实义动词 dare
肯定句& 现在时& dare to 少用&&&&&&&&&& dare/dares to do
&&&&&&& 过去时& dare to 少用&&&&&&&&&& dared to do
否定句& 现在时& daren’t/dare not do&&& do/does not dare (to) do&
&&&&&&& 过去时& dared not do&&&&&&&&&& did not dare (to) do
疑问句& 现在时& Dare he do?&&&&&&&&&&&& Do you/Does he dear (to) do?
&&&&&&& 过去时& Dared he do?&&&&&&&&&& Did he dare (to) do
&&& （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：
&&& 1）According to the weather forecast, it may rain tomorrow.
&&& 2) 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 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.
&&& 2）He is able to give up his bad habits.
&&& 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：
&&& 1）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 +v, be used to +v-ing和be used to +v
&& （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 me to speak yesterday.
其他回答 (2)
情态动词的用法嘛情态动词所表达的可能性程度：must/can't ? should/shouldn't ? might/may (not) 另外两个"类情态词的形式："need/needn't; have to/don't have to ? 最自然的虚拟状态：由should/would+原型时态（不含时间只含状态） 本质上是过去将来时：即，时间固定在过去将来，状态不同：一般、进行、完成、完成进行。 这时"虚拟语气"的产生往往是因为我们要表达"本来应该……"（而现在却还没有……） （本来可以……，本来能……） I should go! (… but I'm still here!) (一般) I should be working now! (进行) I should have practiced more (than I did)! (完成) 我应该多多练习！（言下之意，现在我练习得不多。） I shouldn't dream away my time too much! (完成的否定) (actually I did dream away my time too much!) It shouldn't have been leaking for such a long time! (完成进行) I may/might/could have finished! (完成) 一些常见的句型中，就会出现这种虚拟语气，而处于从句之中，should 常常被省略掉 o suggest, advise, propose, recommend, o demand, order, direct, arrange, command, o require, o think, expect, believe, insist, suspect. 由于他们的含义中包含"建议，假设，应该"这类的含义，所以，由他们引起的从句中，就会包含有should+原型时态构成的虚拟语气。 这些动词（以及他们的名次形式，分词形式）引起的从句还有其他的变形： 主语从句，表语从句，同位语从句 It's suggested that… My suggestion is that… The only suggestion that... The only suggestion I can give you now is that… 一些形容词引起的表语从句中，也会有同样的情况
essential It' incredible that
no wonder ? 由lest, for fear that, in case 引起的从句中多使用should ? 表达与事实相反 1. 与现在相反：使用[过去时]： I wish I were not here! (一般现在?一般过去) Suppose we were not here. He loved me as if I were his own son. (一般现在?一般过去) Hope I weren't always losing things! (现在进行?过去进行) If only/If I hadn't been there! (现在完成?过去完成) What if I hadn't been waiting right here! (现在完成进行?过去完成进行) 常考句型：It's (high) time (that)…; would rather (that)… 这两个从句，只能表达对现在的看法，所以，从句中只有一般过去时。 2. 与过去相反：过去完成时； How nice it is if I had past the test! How nice it is if I had slept a little more this morning! 3. 与将来相反？将来的事情没有发生，所以只能推测。 If it rains tomorrow, we'll have to stay one day more. 不过，由于可以用be to表示将来；所以，虚拟语气中经常出现were to；也是CET-4的常考语法点。 ? 虚拟条件句 o if 部分，做一个与事实相反的假设（所以只有一般过去和过去完成）； o 主句部分，这是表示基于这个假设的推测，一般使用情态动词would，少数情况下使用could/might/may。 o 注意：两个部分之间，是有逻辑关系，而在两部分的谓语动词时态上，没有必然的联系。 ? 注意，虚拟条件句中的if可以省略，造成were/had提前，产生倒装。 ? 隐含的非真实条件 What would you do with 50 thousand dollar? How could I be happy without you? 除了条件状语从句之外，原因状语从句也会出现虚拟语气。 o 由in order that, so that引起的从句，肯定的时候可以使用may/ can/ 否定的时候，多用shouldn't; o whoever, whatever, no matter what引起的从句中，多用may+ 情态动词的基本用法及其区别 最近几年高考试题中常常借助语境来考查情态动词的基本用法及其区别，因此在平时学习时准确理解和掌握情态动词的基本用法十分重要。情态动词的用法复杂多变，在高考试题中，命题者常常利用语境和句子之间意义上的细微差别来考查学生对情态动词的理解和掌握。对于情态动词，除了要求考生能够准确掌握它们的基本用法外，还要充分利用高考试题所设置的语境来分析句子之间所体现的特殊关系。下面就近几年来高考试题中出现的情态动词的考点进行归纳分析，以便同学们复习掌握。 一、用“情态动词＋have ＋done”结构表示对过去动作的推测，高考试题中常用过去时态或过去的时间状语给以暗示。情态动词的这一用法可以用 “对立统一”来概括。 1．当试题的前句和后句在动作和意义上相互补充说明，且整个句意在动作和时间上是一个整体时，我们可用“统一”关系来解决这样的试题。常见的结构有： must have done： 表示对过去动作的肯定推测，常译作“一定做了……”，只能用于肯定句中。其否定形式为can’t／couldn’t have done? 疑问式为Can／Could...have done？。 could ／might have done：表示对过去发生的动作的可能性推测，常译作“可能做了……”。如： 1) My sister met him at the Grand Theater yesterday afternoon, so he ＿＿＿＿＿ your lecture． ? A． couldn’t have attended B． needn’t have attended C． mustn’t have attended D． shouldn’t have attended 本题选A。 2) Jack ＿＿＿＿ yet, otherwise he would have telephoned me． A． mustn’t have arrived B． shouldn’t have arrived C． can’t have arrived D． need not have arrived （C） 2．当试题的前后句在动作和意义上构成转折关系时，常借助“but, however, instead”等词来表示过去的动作与客观事实不符，这时我们就可以用“对立”关系来解决这样的试题。这种结构常见的有： should have done ／ ought to have done：表示过去本应该做某事而实际上没有做。 should not have done ／ ought not to have done：表示过去本不应该做某事但事实上却做了。 need have done：表示过去本来有必要去做某事，但事实上没有做。 need not have done：表示过去本来没有必要做某事，但事实上却做了。如： 3) I was really anxious about you． You ＿＿＿＿＿ home without a word． (NMET2001) A． mustn’t leave B． shouldn’t have left C． couldn’t have left D． needn’t leave “本不应该离家出走却走了”，故本题选B。 4) I told Sally how to get here, but perhaps I ＿＿＿＿＿ for her． (NMET’94) A． had to write it out B． must have written it out C． should have written it out D． ought to write it out 由句中的连词but可知前后句之间是对立关系，分析题意可知本题应选C。 二、考查情态动词基本用法之间的比较和辨析。最近几年高考试题中常借助具体的语境来考查考生对那些最常见的情态动词的基本用法的理解和掌握，因此在做这样的试题时应认真分析语境中所含的实际意义，并结合情态动词的基本含义和用法做出正确的选择。 5) —Is John coming by train？ —He should, but he ＿＿＿＿＿＿ not． He likes driving his car． A． must B． can C． need D． may mustn’t 表示“禁止、不准”；cannot 表示“不可能”；need not 表示“不必要”；may not 表示“可能不”。分析语境可知本题应选D。 6) —I hear you’ve got a set of valuable Australian coins． ＿＿＿＿＿＿ I have a look？ —Yes, certainly． A． Do B． May C． Shall D． Should 分析语境可知这是在征求对方的许可，may表示“允许、可以”，语气比较委婉? shall常用于第一、三人称作主语的疑问句中,表示征求对方意见和指示，如果此空用shall，则意为“要（我）看一下吗？”，不符合上下文意思。故本题选B。 7) Mr Bush is on time for everything． How ＿＿＿＿ it be that he was late for the opening ceremony？ A． can B． should C． may D． must must be 表示肯定的猜测，只能用于肯定句中，由题意可知本题应选A。 8) —Are you coming to Jeff’s party？ —I’m not sure． I ＿＿＿＿ go to the concert instead． A． must B． would C． should D． might 由题意和下句中的 “I’m not sure” 可知这段对话中存在一种可能性推测，might可以用来表示一种比较委婉的可能性判断，故本题选D。又如： I should have been there, but I ＿＿＿＿＿ not find the time． A． would B． could C． might D． should 分析题意可知第二个分句表示过去的某种能力；C 项只表示语气上的可能性，与题意不符。故本题选B。 9) Johnny, you ＿＿＿＿ play with the knife, you ＿＿＿＿ hurt yourself． A． won’t; can’t B． mustn’t; may C． shouldn’t; must D． can’t; shouldn’t mustn’t 表示“不可以；禁止”，分析题意可知第二个空表示某种可能性，故本题选B。 10) —Will you stay for lunch？ —Sorry, ＿＿＿＿＿＿． My brother is coming to see me． A． I mustn’t B． I can’t C． I needn’t D． I won’t 分析题意可知因为“我弟弟要来看我”，所以“不能留下”，因此对别人的邀请或要求应给予礼貌的拒绝。A 项表示“禁止”；C项表示“不必要”；而D项表示“不会”，均不符合题意。故本题选B。又如： —Could I borrow your dictionary？ —Yes, of course you ＿＿＿＿＿． A． might B． will C． can D． should (C) 11)—When can I come for the photos？ I need them tomorrow afternoon． —They ＿＿＿＿＿ be ready by 12?00． A． can B． should C． might D． need 该题考查情态动词should的基本含义，分析句意可知本题应选B。又如： 12) The fire spread through the hotel very quickly but everyone ＿＿＿＿ get out．( A． had to B． would C． could D． was able to 该题考查了could和be able to的区别，二者都可表示过去时间的能力，但如果表示过去成功地做了某事只能使用was ／ were able to do，故本题选D。 13) —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 情态动词shall在试题中表示征询对方意见或请求指示。答句暗示 “没有必要了”，故本题选A
不就是问个简单的东西么 搞那么复杂干吗 can must could might表示推测的时候 can多用于否定句 而must could might 按其可能性排列 用法无区别
那让你选could还是can，may还是might该怎么选？
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外语领域专家may might以上每组有什么区别,分别应用在什么时候?_百度作业帮
may might以上每组有什么区别,分别应用在什么时候?
以上每组有什么区别,分别应用在什么时候?
1. can (could) 1）表示能力,could主要指过去时间. Two eyes can see more than one. 两只眼比一只眼看得清. Could the girl read before she went to school? 这女孩上学前能识字吗? 2）表示可能（理论上或是逻辑判断上）. The temperature can fall to –60℃, that is 60℃ below freezing. 气温可降至—60℃,也就是零下60℃. He can&t (couldn&t) have enough money for a new car. 他不可能有足够的钱买新车. You mustn&t smoke while you&re walking around in the wood. You could start a fire. 在林子里走时勿吸烟,那样可能会引起火灾. 3）表示允许. Can I have a look at your new pen? 我可以看一看你的新钢笔吗? He asked whether he could take the book out of the reading—room. 他问他可不可以把书带出阅览室. 4）表惊异、怀疑、不相信等态度.主要用于否定句、疑问句或感叹句中. Where can (could) they have gone to? 他们会去哪儿了呢? He can&t (couldn&t) be over sixty. 他不可能超过六十岁. How can you be so careless? 你怎么这么粗心? 5）比较委婉客气地提出问题或陈述看法. Can (Could) you lend me a hand? 帮我一把好吗? I&m afraid we couldn&t give you an answer today. 恐怕我们今天不能给你答复. 2. may (might) 1）表允许,might可以指过去时间,也可指现在时间,语气更委婉. You may take whatever you like. 你喜欢什么就拿什么. He told me that I might smoke in the room. 他告诉我可以在房间里抽烟. May (Might) I ask for a photo of your baby? 我可以要一张你宝宝的照片吗? 在回答以may引起的问句时,多避免用这个词,而用其它方式,如Yes, please. / Certainly. / Please don&t ./ You&d better not. / No, you mustn&t.等,以免显得太严峻或不客气. 2）表可能（事实上）.可以指过去时间,也可以指现在时间,但语气更加不肯定. He may be at home. 他可能在家. She may not know about it. 她可能不知道这件事. He was afraid they might not agree with him. 他担心他们可能不同意他的意见. They might be having a meeting, but I&m not sure. 他们有可能在开会,不过我不肯定. 3. must 1）表示义务.意为“必须”（主观意志）. We must do everything step by step. 我们一切都必须循序渐进地做. You mustn&t talk to her like that. 你不可能那样对她说话. --Must we hand in our exercise—books now? 我们现在就要交练习本吗? --No, you needn&t. / No, you don&t have to. 不必.（这种情况下,一般不用mustn&t） 2）表示揣测.意为“想必、准是、一定”等,只用于肯定句. He must be ill. He looks so pale. 他准是病了.他的脸色苍白. She&s wearing a diamond necklace. She must have a lot of money. 她戴着钻石项链,一定很有钱. 4. shall 1）表征询意见,用于第一、第三人称疑问句. Shall I get you some tea? 我给你点茶好吗? Shall the boy wait outside? 让那男孩在外面等吗? What shall we do this evening? 我们今晚做什么? 2）表说话人的意愿,有“命令、允诺、警告、决心”等意思,用于第二、第三人称陈述句. You shall do as I say. 按我说的做.（命令） You shall have my answer tomorrow. 你明天可以得到我的答复.（允诺） He shall be sorry for it one day, I tell you. 有一天他会后悔的,我告诉你.（警告） Nothing shall stop us from carrying out the plan. 什么也不能阻止我们执行这项计划.（决心） 5. will 1）表意愿,用于各种人称陈述句. I will do anything for you. 我愿为你做任何事. None is so blind as those who won&t see. 不愿看的人眼最瞎. If you will read the book, I&ll lend it to you. 如果你愿意读这本书,我会把它借给你. 2）表请求,用于疑问句. Will you close the window? It&s a bit cold. 请你把窗户关上好吗?有点冷. Won&t you drink some more coffee? 再来一点咖啡好吗? 3）表示某种倾向或习惯性动作. Fish will die out of water. 鱼离开水就不能活. The door won&t open. 这门打不开. The boy will sit there hour after hour looking at the traffic go by. 那男孩常常坐在那里好几个钟点,看着车辆行人通过. 6. should 1）表义务.意为“应该”（某件事宜于做）,用于各种人称. You should be polite to your teachers. 你对老师应该有礼貌. You shouldn&t waste any time. 你不应该浪费时间. 2）表推测,意为“想必一定、照说应该、估计”等. The film should be very good as it is starring first—class actors. 这部新电影是一流演员主演的,估计拍得很好. They should be home by now. 照说他们现在应当已经到家了. 7.would 1）表意愿. They would not let him in because he was poorly dressed. 他们不让他进去因为他衣着破旧. I said I would do anything for you. 我说过我愿意为你做任何事. 2）表委婉地提出请求、建议或看法. Would you like another glass of beer? 再来杯啤酒好吗? Would you mind cleaning the window? 请把窗户擦一下好吗? They wouldn&t have anything against it. 他们不会有什么反对意见. 3）表过去反复发生的动作或过去的一种倾向. Every time she was in trouble, she would go to him for help. 她每遇到麻烦都会向她求助.他告诉我盒子打不开了. （二）情态动词后跟完成式和进行式的用法 1.情态动词后跟完成式,表“应当已经……”,“想必已经……”,“本来可以……”等意. I should have finished the work earlier. 我应当早一点完成这项工作的. He isn&t here. He must have missed the train. 他还未到,一定是没赶上火车. Where can (could) he have gone? 他能到那里去了呢? You may (might) have read about it. 你可能在报上已经读到这件事了. You could (might) have been more careful. 你本来可以更细心的. He needn&t have worried about it. 他本不必为此事担心. There was a lot of fun at yesterday&s party. You ought to have come, but why didn&t you? 昨天的聚会非常有意思.你本应该来,为何不来呢? 2. 情态动词后跟进行式,表示“想必正在……”,“可能正在……”,“应当正在”等意. It&s twelve o&clock. They must be having lunch. 现在是十二点.他们一定正在吃饭. They may be discussing this problem. 他们可能正在论讨这个问题. He can&t be telling the truth. 他说的不可能是真话. She shouldn&t be working like that. She&s still so weak. 她不应当那样干,她身体仍那么虚. （三）几组词的辨异 1. can 和be able to 1）情态动词can只有两种时态形式,现在式can和过去式could,而be able to有多种时态形式. Mary can play the piano. She has been able to play it since she was 5. 玛丽会弹钢琴.她五岁起就会弹了. 2）用在过去时中,could经常表示能够做某事,事实上不一定去做,而was∕were able to则表示“过去做成了某事”.在否定句中两者可通用. He could swim across the English Channel. But he didn&t feel like it that day. 他能游过英吉利海峡,但那天他不想游. Yesterday I was able to get home before the heavy rain. 昨天我在下大雨前赶到了家里. 2. must和 have to must表示主观意志,而have to表示由于客观因素不得不做某事.must没有过去式,除在间接引语中可用于表示过去时间,在直接引语中表示过去时间应该用had to代替. I told her that she must give up smoking. 我叫她必须戒烟. We had to get everything ready that night. 我们那晚得把一切准备就绪. 3. would和used to 1）used to表示过去与现在或过去某时与后来的情况有不同,而would只表过去的情况. People used to think that the earth was flat. 过去人们认为地球是平的.（现在人们不这么认为.） She would go out for a walk in the morning when she was in the country. 在乡下时,她总是在早晨去散会儿步.（可能现在仍有散步的习惯.） 2）used to可表示过去的习惯动作和经常的情况,而would只表示过去的习惯动作. He used to ∕would smoke while writing. 过去他写东西时常抽烟. She used to be fat. 她过去很胖
情态动词主要有can/could，may/might，must，shall/should，will/would，need，ought to等。情态动词具有如下特征：
1.情态动词本身具有意义，而且在不同场合表示不同的情态意义。例如：
You must finish the homework first.你必须先完成家庭作业。
The road is wet. I...
will是将要
shall{我不知道}
should应该
must 一定{一般是用于规则}
may might {不知道}
我才小学6年级
有很都不懂啦`~~~~~~~~~~~~~~~~~~~~~}