need"不必做"和"本不该做"

need"不必做"和"本不该做"

didn't need to do表示： 过去不必做某事, 事实上也没做。.

　needn't have done表示： 过去不必做某事, 但事实上做了。

　John went to the station with the car to meet Mary, so she didn't need to walk back home. 约翰开车去车站接玛丽，所以她不必步行回家了。

　John went to the station with the car to meet Mary, so she needn't have walked back home. 约翰开车去车站接玛丽，所以她本不必步行回家了。 (Mary步行回家，没有遇上John的车。)

典型例题

　There was¹ plenty² of time. She ___.

A. mustn't have hurried　 B. couldn't have hurried　　C. must not hurry　 D. needn't have hurried

　答案D。needn't have done. 意为"本不必"，即已经做了某事，而时实际上不必要。

　Mustn't have done 用法不正确，对过去发生的事情进行否定性推断应为couldn't have done, "不可能已经"。 must not do 不可以（用于一般现在时）。

重点词汇点拨

1 was

v.(is,am的过去式)是，在

参考例句：

• He said he was right.他说他是正确的。
• He was cold and hungry.他又冷又饿。

2 plenty

adj.充足的，相当多的；n.充足，大量；pron.充分，够多

参考例句：

• We have plenty of time to finish the job.我们有充裕的时间完成这项工作。
• Plenty of people have come.来了很多人。