儿童必须使用经过认可的儿童安全带或成人座椅安全带。

Children must use an approved child restraint or adult seat belt.

《牛津词典》

你必须使用正确的手型。

You have to use the correct hand shape.

youdao

例如，农民必须使用很多化学药品来种植棉花。

For example, farmers have to use a lot of chemicals to grow cotton plants.

youdao

You handle them very special in terms of being extra careful in a very high ventilation area, in hoods is how you handle them.

在使用它们的时候你需要格外小心,必须在通风条件非常好的地方，在通风柜中才行。

麻省理工公开课 - 化学原理课程节选

This material will be necessary to do the listening exercises for the course, which is sort of the backbone of the course.

做听力练习时我们必须使用这些材料,听力训练是课程的核心内容

耶鲁公开课 - 聆听音乐课程节选

It's a common mistake to make if you forget that I've actually declared that variable up top, but wait a minute, I know any time that I use a variable, I have to declare it.

这是一个通常犯的错误，如果你忘了,之前在前面已经声明了这个变量，等等，我知道在任何时候,我使用一个变量，我必须声明它。

哈佛公开课 - 计算机科学课程节选