It's very quiet upstairs; they must be up to some mischief !

楼上很安静。他们一定在搞什么恶作剧。

《牛津词典》

The taxi driver reeled off a list of historic edifices they must not fail to visit.

出租车司机一口气说出了一串他们不应错过参观的历史建筑。

《柯林斯英汉双解大词典》

Wendy, who saw that they must break the joyous news more gently, had a better plan.

温迪觉得他们必须把这个令人高兴的消息更温柔地说出来，她有了一个更好的计划。

youdao

They have less than two weeks to go before they must perform the play for the Shakespeare in the Courts program.

VOA: special.2010.06.03

The losing side must come to the winning side and they must ask permission to pick up their dead and bury them.

战败方必须出使战胜方,征求胜方同意,让他们可以,拣回本方死者的尸体进行安葬

耶鲁公开课 - 古希腊历史简介课程节选

The point is just if I can at least imagine the one thing without the other, they must in fact be two separate things.

我们要讨论的是,至少如果我可以想象,某物独立于另一物存在,那么它们就肯定彼此不同

耶鲁公开课 - 死亡课程节选

If they concede a goal they must concentrate on not letting in three or four.

BBC: Confidence is key for Scotland

If employers give only 30 days notice, then they must pay 30 days severance.

FORBES: Layoffs And Lawsuits

"They must have felt they couldn't respond in the way they would have liked to, " she said.

CNN: Were U.S. troops told to overlook Afghan abuse of boys?