His health requires that he ________ to bed early.
Studies show that sunshine, fresh air, and plenty of rest often _______ a person’s recovery from sickness.
He has little acquaintance _______ music , while he has a wide knowledge ____ painting.
He insisted what he did _______ right and that anyone who broke laws ________.
It’s uncertain _______ side effect the medicine will bring about , although about two thousand patients have taken it .
--Sorry, I have to _________ now. It is time for class. --- OK, I’ll call back later.