It must be hard for her, bringing up four children on her own.

她一个人抚养四个孩子一定很艰难。

《牛津词典》

Mike: It must be hard work.

迈克： 这一定很难做。

youdao

It must be hard work.

这一定很难做。

youdao

Must be hard being brothers.

VOA: standard.other

So this must be the Nash Equilibrium, that wasn't hard, right?

这点就是纳什均衡了,这不难是吧

耶鲁公开课 - 博弈论课程节选

It must be really hard.

一定很难。

学习是生活的一部分 - SpeakingMax英语口语达人

While we value beauty, it must be hard to go into meetings knowing that almost every man in the room is imagining what you looking like in a bikini in 1984.

FORBES: Can Beautiful Women Be Taken Seriously in Business?

It must be hard just now.

NEWYORKER: Noble Savages

Ms. LAKE: It is hard, and I think it must be really hard on observers now.

NPR: As Election Day Nears, Poll Data Questioned