3.对于用need的提问, 肯定回答用must, 否定回答用needn’t

　　　 　　a. Need I come? Yes, you must. / No, you needn’t.

2.need作情态动词时, 多用于否定句及疑问句中, 不用于肯定句中

　　　 　　a. It is still early. You needn’t hurry. =You don’t need to hurry.

　　　 　　b. It is 11 o’clock. Need I go now? =Do I need to go now ?

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.