You mustn't leave the gate open.

你一定不要让大门敞开着。

《牛津词典》

You mustn't say things like that.

你千万别说那样的话。

《牛津词典》

Keep down! You mustn't let anyone see you.

蹲下！一定不要让人看见你。

《牛津词典》

Frost says at the time that he's publishing A Boy's Will, to a friend: You mustn't take me too seriously if I now proceed to brag a bit about my exploits as a poet.

他在发表第一本书时对一个朋友说：,不要对我太认真,如果我现在吹嘘自己已是一位诗人。

耶鲁公开课 - 现代诗歌课程节选

You shouldn't be able to hear very much either, and it mustn't have been too delightful to breathe out of the thing, although your nose is free, but it's covered by a nose piece.

而且也听不见什么了,同时,戴着头盔呼吸也不是很顺畅,虽然鼻子并不受束缚,但是上面有一块小薄片覆盖着

耶鲁公开课 - 古希腊历史简介课程节选

"You mustn't start fixing up the closets and taking Aunt Lucy to the doctor because you're the only one at home, " she says.

FORBES: Magazine Article

"You mustn't do that kind of thing, " his instructor said.

BBC: Robert Smith-Barry: The man who taught the world to fly

Not playing can get you down, there are going to be good and bad moments, but you mustn't sulk - you've got to make sure you're ready if needed.

BBC: Keeping the chin up