I think _____ necessary to accept his advice because it’s of great ______ to me,
I don’t remember _____ the book yesterday.
—Do you know___? —He is a dentist.
—Excuse me, could you tell me where_____? — Sure, sir. You can try
— I don't know______. — Because he has to look after his mother.
— Could you tell us how long ___? — About three days.