----Hello! What are you doing now? 

----We ____________ the school trip.

A．are enjoying

B．are enjoy

C．enjoying

D．enjoys

进站色灯信号机显示一个绿色灯光和一个黄色灯光，准许列车经岔道直向位置，进入站内越过次二架已经开放的信号机准备停车。