情态动词ought to
编稿：张桂琴  审稿：梁晓
概念引入
Such things ought not to be allowed. 这类事不该容许。
He said I ought to write an article about it. 他说我应当写一篇文章谈这事。
I ought to be fit for work next month. 下个月我想必可以工作了。
I don’t think you ought to have done that. 我想你不应该这样做的。
语法讲解
ought to的用法讲解
ought to是一个比较奇怪的情态动词，因为其他所有情态动词都后接动词原形，而ought to虽然也是后接动词原形，但却无意中构成了ought to do sth结构，其中的to do sth.便是一个典型的
带to不定式，并且ought to do sth在用法上也是基本上将ought与to do sth
分开使用——如构成疑问句，只需将ought提前，而不是将ought to提前；构成否定式时，是在ought后面加上not，而不是在ought to的后面加not。如：
Ought I to tell her the truth? 我应该把真实的情形告诉她吗？
We ought to be careful， oughtn’t  we? 我们应该小心，对吧?
Oughtn’t  he to see a doctor? 他是不是该去看医生?
You oughtn’t  to stay out so late. 你不应当在外面待到这样晚。
在美国英语中，ought to用于否定句和疑问句时可将其中的to省略。如：
Ought we (to) have done it? 我们本该做此事吗?
但是，肯定句中的to通常是不会省略。另外，在简略答语中，有时也可以省去to。如：
—Ought he to go with us? 他应该同我们一起去吗?
—Yes, he ought (to). 对，应该一起去。
意义如下：
（1）ought没有人称或时态的变化，后跟带to的不定式。常译作“应该”，“应当”等，和should同义，只是口气稍重一些。其否定式为ought not to (oughtn't to )，疑问式为Ought I /you to…?
You ought to start at once你应该立刻出发。
Such things ought not to be done.这种事不应该干。
-Ought he to go? 他应该走了？
-Yes, he ought to.是的，应该走了。
（2）表可能性
Mary ought to be home by now.玛丽这会儿该是到家了。
There is a fine sunset. It ought to be a fine day tomorrow.今天有晚霞，明天应该是个好天。
It ought to be a fine day tomorrow morning.明天旱晨大概是个好天气。
（3）表示没有履行过去的义务时，用“ought to +完成时。
You ought to have told me about this earlier.(But you didn't)你本来应该早一点把此事告诉我。（但没有）
I ought to have written that letter yesterday.(But I didn't)我本应该昨天写那封信。（但我没写）
It ought to have been done long ago.这事早该做完的。
二、ought to的否定式和疑问式 
1. ought to的否定形式是ought后直接加not构成，其否定形式可缩写为oughtn't。 
One ought not (oughtn't) to cross the street against the red light. 
2. ought to的疑问式是将ought提到句首构成。 
—
Ought we to do it at once? —Yes, you ought to. 
在反意疑问句里，下面两种形式都可以： 
He ought to be here now, shouldn't (oughtn't) he? 
"必须 ,应该, 应当"的意思，ought to与should意思接近，大多数情况下二者可以互换，但是should谈的是自己的主观看法，ought to则更多反映客观情况，在谈到法律、义务和规定时使用。 
ought to具体用法如下： 
1. (表示义务、责任等) 应当, 应该 
You ought to work harder than that. 
2. (表示劝告、建议等) 应该, 该 
You don't look well. You ought to go to see the doctor. 
3. (表示猜测、期望) 总应该，理应 
It ought to be a fine day tomorrow morning. 
4. “ought to + have + 过去分词”表示过去应做某事而实际未做 
You ought to have told me that (but you didn't). 
这时ought to和should可以互换使用。 
ought to的否定式和疑问式 
ought to的否定形式是ought后直接加not构成，其否定形式可缩写为oughtn't。 
should和ought的区别
两者可替换，ought to语气稍重。在公告、须知或条例中，出于礼貌，常用should. 
表示出于法令规则、行为准则、道德责任等客观情况而“应该”做某事时，一般应用ought to，若用should则含有个人意见，强调主观看法。
二者区别： 
ought to比should 语气强 
（1）should 表示主观看法，一些建议，劝说时，译作“应当”。 
ought to，直接接动词原形，更多反映客观情况，“有义务”或“必要”做某事，译为“应当，应该” 
（2）ought to的否定就表示做某事一定是错误的 
而should的否定就表示某动作不一定要做 
3.should可以用于虚拟语态, 
而ought to 不能 
ought to 是唯一一个可加to的情态动词! 
ought to 比should语气更强烈 
ought to的否定就表示做某事一定是错误的 
而should的否定就表示某动作不一定要做 
表示应该，责备时 区别不大 但是should可以在名词从句中表示虚拟如在suggest, advise,等从句中 在lest, for fear that, in case等的状语从句中也只用should 另外should有表示惊讶之意 
ought to与should意思接近，大多数情况下二者可以互换，但是should谈的是自己的主观看法，ought to则更多反映客观情况，在谈到法律、义务和规定时使用。 
如： We should／ought to help each other and learn from each other in our work． 
She is your mother, so you ought to support her． 
We ought to go and see Mary tomorrow, but I don’t think we will． 
ought to具体用法如下： 
1. (表示义务、责任等) 应当, 应该 
You ought to work harder than that. 
2. (表示劝告、建议等) 应该, 该 
You don't look well. You ought to go to see the doctor. 
3. (表示猜测、期望) 总应该，理应 
It ought to be a fine day tomorrow morning. 
4. “ought to + have + 过去分词”表示过去应做某事而实际未做 
You ought to have told me that (but you didn't). 
这时ought to和should可以互换使用。 
情态动词ought to和had better用法详解
ought to+原形动词表示义务、劝告或推测等意义，意思是"应该…". 
  I am tired. I ought to sit here for a while. 
  我累了，我应该休息一会儿。 
  表示否定时,not放在ought之后。在美语中,在否定句中,ought之后的不定词符号to常可    省
略。 
  Hey, boy, you oughtn't （to） sleep here. Get up! 
  嘿，孩子，你不应该躺在这儿。起来！ 
  在美语中,在疑问句中,ought之后的不定词符号to常可省略。react to啥意思 
  Ought you （to） do it? 
  你应该这么做吗？ 
  had better只有一种形式,不是表示过去,而是指现在或未来,表示向对方提出劝告或警告。              had better+原形不定词表示"最好……". 
  You had better give up smoking. 
  你最好把烟戒掉。 
  had better的否定形式是had better not. 
  You had better not throw it on the ground. 
  你最好别把它扔在地上。 
had better很少用于疑问句,但有时为了表示忠告或建议而用否定疑问句,这时否定副词                    not位于主语之后。 
  Had you better not talk to yourself? 
  你不要自言自语好不好?
【高清课堂：情态动词356516情态动词  表推测的情态动词】
表示推测的情态动词：
肯定推测: 用must, may, might。
注意：must/may/might have done。
He must be the new teacher.
They must have come from Shanghai.
They may/might have had a cold.
否定推测: 用cannot, cannot/couldn’t have done。
She cannot be his daughter. She is too old.
They cannot/couldn’t have caught the 9:15 train, for they left the hotel at 9:20.
He can’t have heard us. Knock again.
need
情态动词: 常常用于否定和疑问句。
You don’t need to tell Susan. She knows it.
— Need I tell you where you are?
— No, you needn’t.
实意动词:
She needs help. She needs to have an ID card.
You don’t need to go there to have your exam.
need doing
dare
He dares to do anything, but this time he dare not do.
I dare not ask him questions.
Dare he tell them what happened yesterday?
He doesn’t dare to go there by himself.
He will never dare to come again.
ought to=should
We ought to love others as ourselves.
You oughtn’t to smoke that much.
They ought not to have gone there yesterday.

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