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。
8. ought to
1）表义务，意为“应该”（因责任、义务等该做），口气比should稍重。
You are his father. You ought to take care of him. 你是他父亲，应当管他。
You oughtn't to smoke so much. 你不应该抽这么多烟。
2）表推测，暗含很大的可能，语气较弱。
Han Mei ought to know his telephone number. 韩梅该知道他的电话号码。
There's a fine sunset； it ought to be a fine day tomorrow. 今天有晚霞，明天应该是个好天。
9. used to
表示过去的习惯动作或状态，现在不复发生或存在。疑问式和否定式有两种。
He used to live in the countryside，but now he lives in the city.他过去住在乡下，现在住在城里。
There used to be a building at the street corner，but it has been pulled down.
街道拐角处过去有座楼房，现在拆了。
I usedn't （didn't use） to smoke. 我过去不抽烟。
Used you （Did you use） to go to school on foot？ 你过去常步行去学校吗？
（一）need和dare的用法
need和dare既可用作情态动词，也可用作实义动词。用作情态动词时，主要用于否定句和疑问句。用作实义动词时，可用于各种句式。
1.用作情态动词
——Need I come？ ——Yes，you must. ——我需要来吗？ ——需要。
You needn't telephone him now. 你现在不必打电话给他。
I don't think you need worry. 我想你不必发愁。
She dare not go out alone at night. 她晚上不敢一个人出去。
How dare you say I'm unfair？ 你竟敢说我不公平？
Not one of them dared mention this. 他们谁也不敢提这件事。
2.用作实义动词
You don't need to do it yourself. 你不必亲自做这件事。
We need to tell them the news. 我们需要把这消息告诉他们。
The table needs painting （to be painted.）。 桌子需要油漆一下。
We should dare to give our own opinion. 我们要敢于提出自己的观点。
He did not dare （to） look up. 他不敢抬头看。
I dare day he'll come again. 我想他会再来的。
（I dare say…为固定习语）
（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。