Our manager ________ for Shanghai in a few days and he has asked me to find out when the earliest plane ________ next Wednesday.

A．is leaving; takes off

B．will leave; is taking off

C．leaves; will take off

D．is to leave; is going to take off

（）的主要理化性能颗粒度、交换容量、机械强度、膨胀度、含水量、密度、孔结构。