I must finish the task before dark.

我必须在天黑以前完成任务。

You mustn’t lend my book to others.

你不许把我的书借给别人。

— Must I do the cleaning right now?

我现在就必须打扫吗？

— Oh, no, you needn’t. You may do it in the afternoon.

不必。你可以下午打扫。

All men must die.

人总有一死。

He must always have his own way.

他总是自行其是。

He said he must see you.

他说一定要见你。

His new novel is a must for all lovers of crime fiction.

他的新作是所有侦探小说爱好者的必读书。