异响的常见成因包括()
A、空气流动
B、摩擦
C、振动
D、碰撞
参考答案:B, C, D
------- How about your journey to Mount Emei ?
--------Everything was wonderful except that our car ________ twice on the way.
A.slowed down
B.put down
C.got down
D.broke down
We will not be held responsible for any damage which results ________rough handling.
A.from
B.off
C.in
D.to