Ma Yun failed twice in the college entrance exam, making people consider him as _____ failure. But now he has won ______ splendid success in business.

A．\, a

B．a, \

C．\, \

D．a, a

小明和小强对有关惯性和力的知识进行讨论，下列说法正确的是[ ]

A．汽车运动时有惯性，静止时没有惯性

B．汽车刹车时有惯性，匀速直线运动时没有惯性

C．物体受力就运动，不受力就不运动

D．物体在平衡力作用下，运动状态不会发生改变