表示被动含义，这时，need doing＝need to be done。

　　A dog needs taking out/to be taken out for a walk every day.

　　狗得每天带出去遛。

　　2．用作情态动词，后接动词原形，常用于否定句和疑问句中。

　　You needn't finish that work today.

　　你今天不必把那项工作做完。

　　Need he come here?

　　他有必要来吗？

　　3．由need引出的一般疑问句，肯定回答常用must或have to；否定答语常用needn't。

　　-Need I answer the question?

　　--我需要回答那个问题吗？

　　-Yes，you must./Yes，you have to./No，you needn't.

　　--是的，你必须回答。/是的，你得回答。/不，不必了。

　　二、didn't need to do和needn't have done

　　didn't need to do表示过去没必要做某事，实际上也没做。needn't have done表示过去没必要做某事，而实际上做了，常译成"本没有必要做......"。

　　Mary's boyfriend drove to pick her up，so she didn't need to take a taxi.

　　玛丽的男朋友开车去接她，因此她没必要打出租车了。(不需要打出租车，事实上也没打出租车)

　　It was Sunday，so I didn't need to get up early.

　　因为是星期天，所以我没必要早起。(不需要早起，事实上也没早起)

　　We needn't have taken a taxi to get to the museum.It was only five minutes' walk.

　　我们本没有必要乘出租车到博物馆的，走五分钟就到了。(本没有必要乘出租车，但乘坐了)

　　The manager needn't have cleaned the room because it was just cleaned by his assistant.经理本没有必要打扫房间，因为他的助手刚刚打扫过了。(本没有必要打扫，但打扫了)

　　[名师点津]　

(1)在didn't need to do中，need是实义动词；在needn't have done中，need