518　ought to和should

◎ ought to和should意为“应该，应当，总应该”，为情态动词，没有人称、时态变化。

① ought to do sth.可表示责任或义务，指道义上应该做的事。可表示现在、一般将来或过去将来。

We ought to pay what we own. 欠债还钱，理所应当。

You ought to respect the old. 你们应该尊敬老人。

There ought not to be much noise in a hospital. 医院里不该喧闹。

You ought to take part in the meeting tomorrow. 你应该参加明天的会议。

② ought to可表示“应有的结果”或“当然的事”。

You've been roommates for four years，so you ought to know her well. 你们同住一室已有四年了，应该很了解她。

If he started at seven，he ought to be here now. 要是他七点钟出发，这会儿该到了。

He is from Japan；he ought to know Japanese. 他是从日本来的，当然懂日语。

③ ought to在口语中可表示“愿望”。

You ought to read the book twice. 这本书你要看两遍才好。

We ought to see the flower show. 我们去看看花展才好。

④ ought to在语气上比 must 弱，但比 should 强。比较：

You ought to finish the task today. 你应该今天完成这项任务。

You should finish the task today. 你该今天完成这项任务才是。

You must finish the task today. 你必须今天完成这项任务。

⑤ ought to have done sth.表示“应该做某事而未做”，含有责备、遗憾等意。

You ought to have returned the book last week. 这本书你上周就该还的。

Why did you not tell me the truth？You ought to have done so. 你为什么不告诉我实话呢？说了实话就好了。

The child ought not to have been allowed to go alone the other day. 那天，本不该让这孩子一人去的。

⑥ ought to的否定式和疑问式。

A：Ought I to go there？我应该去那里吗？

B：Yes，you ought. 是的，应该。

B：No，you ought not. 不，不应该。

It ought to rain after this long drought，oughtn't/shouldn't it？旱了这么久，也该下雨了，不是吗？

Oughtn't he to give them more care？难道他不该给他们更多的帮助吗？

⑦ should指主观上感到有责任或义务去做某事。should+完成式表示过去的动作，常含有责备、遗憾的意味，表示“本应该，应该已经”，而实际上却没有。

She should have shut the door against him. 她本应该将他拒之门外的。（但没有这样做）