发动机中的飞轮往往是传动系中离合器的（）。
A.驱动件
B.摩擦片
C.传动片
D.压盘
参考答案：A
Can you point to the bottom ____________ the envelope?[ ]
A. on
B. in
C. of
______ it is true that a student’s most important goal is to do well in his or her studies, it doesn’t need to be the only goal．
A．When
B．As
C．While
D．Before
