如果学生几天不能来上课，他们需要提前请假。

Students need to ask for a leave ahead of time if they can't go to school for several days.

youdao

如果学生没有使用手机，手镯的屏幕上会有张照片显示出来。

If the students did not use their cell phones, there would be a photo on the screen of the bracelet to show that.

youdao

如果学生不擅长英语口语，他应该抓住每个开口说英语的机会。

If a student is poor at speaking English, he should catch every chance to open his mouth and speak.

youdao

If the student hasn't mastered the basic concept, we will make sure that the grade scheme gives a failing grade.

如果学生没有掌握基本的概念，我们会确保,成绩将会不及格。

麻省理工公开课 - 固态化学导论课程节选

And finally, we want to position all students so that you can easily, if you like, compete for things like your office and summer jobs.

最后，我们想对所有学生来一个定位,这样一来如果你们喜欢，你们就可以轻松的角逐工作和暑期打工了。

麻省理工公开课 - 计算机科学及编程导论课程节选

But if my students can catch me making a mistake, it means they are following it and they are not hesitating to tell me.

如果我的学生能发现我犯的错误,这证明你们确实在听课,并且愿意直言不讳

耶鲁公开课 - 基础物理课程节选