_____, his suggestion is not useful, though it sounds very interesting. [ ]

A. Generally speaking    

B. To be honest

一辆轿车和一辆卡车在同一公路上均由静止开始同时做匀加速直线运动，加速度大小分别为3 m/s²和7 m/s²，两车能达到的最大速度均为30 m/s，刚开始运动时两车距离为20 m，轿车车身全长5 m，卡车车身全长20 m，则两车的错车时间为

A．1.1 s

B．1.0 s

C．1.2 s

D．1.7 s