--Sorry, I forget ____ my homework . --Don’t do that again.
—Could you tell me ______ ?—By watching English movies.
—______to give back the books to the library before Friday.—OK. I will.
As we all know, a dictionary is a book ______ gives the meaning of words.
—Have you known Mr. Smith for a long time?—Yes, since he ______ to our university.
I didn't manage to repair my car ______ you had told me how.