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

纤维蛋白溶解系统为最重要的抗凝系统，它对保持（）、（）、（）等均有重要作用。