If nobody breaks traffic rules and everyone is careful enough, most accidents can be 　　　.

A．allowed

B．achieved

C．afforded

D．avoided

一辆轿车在平直的公路上匀速行驶，轿车上的速度表如图8所示。在此过程中，若轿车发动机的功率为40kW，则该车行驶中所受阻力为         N。