1.need作实义动词时, 注意以下用法:

①.need to do sth; ②.need sb to do sth; ③.need doing sth (主动形式表被动意义)

　　　 　　a. You need to remain in bed.

　　　 　　b. I need you to help me with the housework.

　　　 　　c. The garden needs watering.( =The garden needs to be watered.)

3.should / ought to的区别:

　 　should / ought to一般可以通用. should侧重于说话人主观上的看法, 有时含有劝告, 建议的口气, 即 “按我的想法应该如何”; 　ought to语气更强, 强调“有责任, 有义务做某事”或者 “按道理应该如何”

　　　 　　a. “I will start the work at once.”　　 “I think you should start at once.”

　　　 　　b. “I will start the work tomorrow.”　 “No. You ought to start at once.”

2.表示推测或推论, 可译为“可能, 应该是”

　　　　 a. He should be home by now, I think.

　　　　 b. He should have arrived in Nanjing by this time.

1.表示义务, 责任, 可译为“应当”

　　　　 a. We should complete the text in time.

　　　　 b. You should be so careless.

4.表示推测, 表示“大概, 也许”的意思

　　　　 a. That would be the pen you are looking for.那也许是你在找的笔吧

3.表示请求, 愿望, 语气客气, 委婉

　　　　 a. I would like some tea.

　　　　 b. Would you mind closing the door ?

　　　　 c. Would you tell me something about your trip ?

2.would do sth可以表示过去经常发生的动作, 相当于used to do sth

　　　　 a. When we were children we would go swimming every summer.

　　　　 b. On Sundays he would go fishing for hours when he lived in the countryside.

1.表示主观意志和愿望, 即“愿意,想要”

　　　　 a. Come here whenever you would.

　　　　 b. He would not leave before he finished his work.

3.must / have to的区别:

　 　①.must / have to一般可以通用, 但must侧重于说话人主观上的看法, 即“说话人认为必须”; have to侧重于客观上的需要, 含有“客观上不得不”之意

　　　 　　a. If the person is not breathing, you must try to start his breathing.

　　　 　　b. You must / have to study with a teacher if you want to know how to do first aid.

　 　②.must没有时态的变化, 一般用于表示现在或将来;　 have to有时态的变化, 可用于过去, 现在, 将来各种时态

　　　 　　a. We must study hard when we are young.

　　　 　　b. I think she must remain in hospital for a week.

　　　 　　c. We had to stay there for a whole day because of the rain.

　　　 　　d. We have to practise a lot if we want to speak English well.

　　　 　　e. The situation has changed; we will have to change our plan.

　 　③.它们的否定式mustn’t / not have to有很大的不同: mustn’t表示“不要(做某事)”, 有禁止之意; not have to表示“不必要(做某事)”, 含有“客观上无此必要”之意

　　　 　　a. You mustn’t move a person if he is badly hurt.

　　　 　　b. You don’t have to be a doctor to do first aid.

2.表示“肯定是, 一定是”的推测意义; 与此对应, 表示“肯定不,一定不”用can’t, 而不用mustn’t

　　　　 a. You must be very tired now.

　　　　 b. If he had really been there, I must have seen him.

　　　　 c. He must have gone away. We don’t see him anywhere.