Children, in my opinion, ________ creative ability is unthinkably rich, ________ is seldom taken notice of by us, should be trained in that area.

A．which; that

B．whose; which

C．which; which

D．whose; that

甲、乙两辆汽车以相等的速率在同一水平弯道的相邻车道做匀速圆周运动，甲车在乙车的外侧．两车沿半径方向受到的摩擦力分别为f_甲和f_乙．以下说法正确的是（　　）

A．f_甲小于f_乙

B．f_甲可能等于f_乙

C．f_甲和f_乙大小均与地面的粗糙程度无关

D．f_甲和f_乙大小均与汽车速率无关