I don’t know －Because he has to look after his mother.

.—I can’t find Mr. Smith. Where did you last see him this morning?—It was in the hotel _______ he stayed.

I didn’t hear your call because I ______ to music at that time.

Mary is a_____student She studies_________.

How about the trip to Shanghai, Kitty?—Everything was fantastic if our car did not _______ for some times on the way.