31. ... be forced/compelled/obliged to do... 不得不做……
Mike was late for school again, so he was forced to clean the classroom after class.
迈克又迟到了，所以他不得不在放学后留下来打扫教室卫生。
People are compelled to take arms in hard times.
在艰难时世，人们被迫拿起武器。
If you make such a mistake again, I shall be obliged to tell your parents.
如果你再犯这样的错误，我将不得不告诉你的父母。
