must
单词辨析：
指因法律、义务、形势等关系而不得不做某事，通常用被动语态。
He was obliged to tell the truth.
他被迫讲出了实情。
Poverty obliged her to live a hard life.
贫困迫使她过艰苦的生活。
The law obliges parents to send their children to school.
法律强制父母送子女入学。
指客观情况迫使某人做某事，侧重于客观上的“必须”。
Did she have to pay a fine?
她非得交罚款吗？
I have to admit that the idea of marriage scares me.
我不得不承认，一想到结婚我就害怕。
指因需要、命令或强制而必得做某事，侧重于主观上的“必须”。
We must take action at once.
我们必须立即采取行动。
I think we must reduce our prices or spend more money on advertising.
我认为我们必须降低价格，或者是在广告上花更多的钱。
相关例句：
Candidates must satisfy the general conditions for admission
候选人必须满足参选的总体条件。
I'm sure he must feel he has lost a close family friend, because I know I do
我敢说他一定觉得自己失去了一位亲密的世交，因为我知道我是这种感觉。
If you must be in the sunlight, use the strongest filter cream you can get
如果一定要呆在太阳底下的话，就擦上你能买到的防晒系数最高的防晒霜。
This must be a very difficult job for you
对你来说，这份工作想必很难。
'Why don't you wear your jogging shorts Mum?' — 'Well, my legs are too skinny, if you must know.'
“妈妈，为什么不穿你的慢跑短裤呢？”——“哦，如果你非要问的话，因为我的腿太瘦了。”
Mr Allen must pay Mr Farnham's legal costs
艾伦先生应当支付法纳姆先生的诉讼费。