用来驱动和控制各缸气门的开启和关闭的零件是（）。
A.凸轮轴
B.曲轴
C.半轴
D.传动轴
参考答案：A
Returning to my hometown, _________.
A．my watch was missed
B．I found my watch missing
C．I found my watch disappearing
D．I found my watch losing
The players expected there ____ more free time before coming back to the country from abroad.
A．is
B．being
C．have been
D．to be
