Protect your hearing. Don’t wait until you ________ hear a thing.
needn’t
mustn’t
shouldn’t
can’t
Our monitor always helps other students ____ their lessons and he never says any bad words _____ others.
Students in the USA spend time their homework than we do.
Chinese students have _________ weeks ______the summer holiday than American students.
We can do the work better with _____ money and ____ people.
We will have a __________test next week.