汽车的布置形式中，发动机前置后轮驱动可表示为（）
A、RR
B、FR
C、FF
D、RF
参考答案：B
The boys even have no time for their homework _________ the basketball match.
A．because of
B．because
C．as
D．since
A．mgtgθ
B．mgsinθ
C．μmg
D．μmg
mgtgθ
mgsinθ