A、  B、  C、  A本句是询问前门为什么锁着的Why疑问句。

Are you planning to go on a business trip soon?
(A)No, he’s at a seminar.
(B)I’m leaving next month.
(C)Do you travel much?

Why is the front door already locked?
(A)Oh, I thought we closed for the day.
(B)It’s the first door on your left.
(C)No, check the locker.