The reason for _______ he failed in the exam was that he was too careless.

A．which

B．why

C．that

D．it

地陪在机场没有接到来自外地的散客，离开机场后地陪应：

A．去完成新的任务
B．回散客部汇报
C．回散客部查明原因
D．去散客预定下榻饭店前台询问