need，must 和 have to 的区别

need:需要；必要；需求；有———必要；贫穷；危急
She feels the need of companionship.
她感到需要友谊。

must:[表示义务、命令或必要]必须, 应当
Soldiers must obey orders.
军人必须服从命令。
【说明】过去、未来、完成等式可用 have to 的相应形式来代替, 例如: I must [have to] do it today. 我必须今天做。
[表示推断或指具有较大的可能性]很可能; 谅必[否定用cannot be, could not have +p.p]

You must be very tired.
你一定很累了。
He must have earned a large sum of money.
他一定是挣了一笔巨款。
[表示主张]一定要, 务必

If it is really lost, it must be found.
如果真丢了, 一定要找回来。
[表示不可避免性或肯定性]必然要, 必定会

Man must die.
人必有一死。
[表示与说话人愿望相反及不耐烦]偏要

Why must it rain on Sunday?
偏要在星期天下雨, 讨厌!
Just as I was sitting down to supper, the telephone mustring.
正当我坐下来用晚餐时, 偏偏电话铃响了。
[方][表示请求]

Must I go now?
我现在可以走了吗?
n.
[口]必须做的事, 必需的东西

The new film is an absolute must.
这部新片不可不看。
adj.
[口]绝对需要的, 不可缺的

must legislation
不可缺少的立法
This is