【2015·天津】We need to get to the root of the problem______ we can solve it.
A man may usually be known by the books he reads _____ by the friends he keeps.
Although he is often tired _____ his work, he is never tired _____ his job. In fact, he enjoys it.
— Is your mother still a teacher?— ______.
Because of the bad weather, my mother ____ and lay in bed. She ______ for a week.
He wishes to make friends with ____ shares his hobbies and interests.