情态动词虽然算是初中英语词汇，是从刚开始学英语就接触到的基本词汇。但要用得和Native Speaker 一样准确，要用的准确表达出自己的强弱心态，却是我们需要额外下硬功夫的。
给大家详细解析一下四组易搞混的情态动词：
o must VS have to;
o should VS ought to;
o can VS could;
o may VS might,
同学们可不要再用错啦——
Must vs Have to
先说Must的用法：
1） Obligation 表达义务
E.g.: You must wear a seatbelt when you drive.
你开车的时候必须系安全带。
2） Deduction表达猜测
*这里要注意的是，如果用must，那么代表你很肯定你的猜测是正确的。
E.g.: Look at all that snow. It must be cold outside.
看看那些雪，外面肯定很冷。
3） Emphasize necessity 强调必要性
E.g.: Plants must have light and water to grow.
植物需要光和水才能生长。
4） Strong recommendation 强烈建议
E.g.: We must get together for dinner soon.
我们一定要尽快一起吃饭。
5） Mustn't = prohibition 表示禁止
E.g.: You mustn't use your phone while driving
开车时禁止使用电话。
Must和Have to 的区别：
1. Must express obligation imposed by the speaker while HAVE TO expresses external obligations.
一句话总结：Must表达了说话者所施加的压力。Have to表达了外部的压力
2. We use “had to” instead of must in the past tense.
在过去时态中，我们用had to代替must。
我们来举一个非常感同身受的例子：
Your teacher may say 'you must complete this essay by Friday.‘， while you say 'we have to complete the essay by Friday.'
老师说的“必须要在周五前完成论文”和学生自己说的“必须要在周五前完成论文”，大家自行感受下…
E.g.: I had to pay my speeding ticket yesterday.
我昨天不得不交了超速的罚款。
3. It is more common to use have to instead of must in questions.
在问句中，have to 常被用来代替must.
E.g.: Does he have to do the test?
他一定要参加那个测试吗？
Mustn't vs don't have to
· Be careful: there is a difference in meaning between “mustn't” and “don't have to”
Mustn't
Meaning：It is prohibited; it is not allowed. It is important that you do not do something
Don't have to
Meaning：There is no obligation; you are not required to do something, especially if you don't want to.
了解了mustn't和Don't have to的意思之后，我们来具体看一下这两个词的用法吧！有实例才能更好的了解词语间的不同——
第一组：
You must not drink that. = Don't drink that, it is not allowed.
VS
You don't have to drink that. = You don't need to drink that but you can if you want to.
第二组：
You mustn't tell john. = do not tell john
VS
You don't have to tell john. = you can tell john if you want to but it is not necessary
这样一看，是不是就对mustn't 和don't have to的区别一目了然啦！其实这两组词还是非常好分辨的——
Should vs Ought to
我们先来看卡should的用法：
1） Advice or suggestion 意见或建议
E.g.: Your hair is too long. Yu should get a haircut.
你头发太长了，你应该剪个头发。
2） Situation likely in the present 现在发生的情况
E.g.: Mary should be at home now. Give her a call.
Mary现在应该在家，打个电话给她。
3） Likely in the future（预测）可能发生在将来
E.g.: They should win tonight, they are the better team.
他们应该能赢，他们是强队。
4） Should + have + past participle
Meaning: the subject did not fulfil their obligation in the past or did not act responsibly. 在过去就应该做的，但没有尽职。
E.g.: You should have given your boss the report yesterday when he asked for it.
你应该在你老板昨天要的时候就把报告给他。
5） Should + be + verb-ing
Meaning: the subject is not fulfilling their obligation now or is not acting sensibly. 并没有尽义务，行为并不明智。
E.g.: You should be wearing your seatbelt.
你应该系安全带的。
E.g.: We should be studying for the test right now.
我们马上应该复习考试。
Should和ought to 的区别：
1. Should can be replaced by ought to without a change in meaning。
*Ought to能够替代should，而句子意思不改变。
E.g.: You ought to study more = you should study more
2. Note: ought to sounds more formal than should and is used less frequently.
*Ought to 相较于should听起来更正式。
3. We use shouldn't to advise not to do something, usually because it is bad or wrong
*我们用shouldn't表示不建议做某事，因为事情本身不好，或者是错的。
E.g.: You shouldn't throw your litter onto the street.
你不应该把垃圾扔在马路上。
Can
Can的用法：
1） General ability （present） 能够（现在）
E.g.: I can speak English.
我能讲英语。
2） Ask for permission （informal） 征求允许（非正式）
E.g.: Can I borrow your pen please?
我能借你的笔吗？
3） To request something 请求做某事
E.g.: Can you help me please?
你能帮我忙吗？
4） Possibility 可能性
E.g.: It can get very cold there at night.
晚上可能非常冷。
5） Offer to help someone 为某人提供帮助
E.g.: Can I carry your bags for you?
我能帮你背包吗？
6） Cannot （can't） = not allowed
E.g.: You cannot smoke in this room.
这个房间里不能吸烟。
Could
Could的用法：
1） General ability in the past 能力（发生在过去）
E.g.: I could play the piano when I was younger.
我小时候能够弹钢琴。
2） Ask for permission （more polite） 征求允许（更礼貌）
E.g.: Could I use your bathroom please?
我能用你的洗手间吗？
3） To request something （more polite） 请求别人做某事（更礼貌）
E.g.: Could you pass me the salt please?
麻烦你把盐递给我吧。
4） Possibility in the past （could + have + past participle） 过去发生某事的可能性
E.g.: You could have broken your leg.
你可能腿断了。
5） Suggestion （when asked what to do） 建议（当被问及做什么时）
E.g.: We could go to the movies if you like.
我们能去看电影如果你愿意的话。
6）Condition of can （would be able to） 虚拟语气
E.g.: If we had some oranges I could make you some fresh juice （= would be able to）
如果我们有橙子的话，我能给你做一些鲜橙汁。
May vs Might
May和Might的共同用法：
1） Possibility 可能性
E.g.: It might rain later so take an umbrella.
等一下可能会下雨，带把伞。
2） Give permission 给予允许
E.g.: You may have another cookie if you like.
你喜欢的话可以再吃一片曲奇。
3） Ask for permission 征求允许
E.g.: May I borrow your pen please?
我能借用你的笔吗？
4） Express wished 表达祝福
E.g.: May the New Year bring you happiness.
祝你新年快乐。
5） Speculate about past actions 对过去行为的猜测
E.g.: She is late. She may have missed her plane.
她迟到了。她可能误机了。
? “May” and “Might” can normally be interchanged without a significant difference in meaning. However, might often implies a smaller chance of something happening （when expressing possibility）。
May和might意思并没有特别大的差别，一般情况下能够互相替换。但当表示可能性的时候，might发生的几率更低。
E.g.: It may rain. （60%）
It might rain. （30%）
When expressing wished or giving permission, only may is used.
当表达祝愿或是给予允许时，只能用may。
上面这些繁杂的区别大家都了解了吗？虽然看着有许许多多细小的分别，貌似很难掌握，但通过多说多写多练习，一定会no problem哒！—— |
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