活塞式发动机的余气系数通常（）.
A.在0.6-1.1之间变化
B.在1.0附近变化
C.余气系数均大于1.0
D.余气系数保持小于1.0
参考答案：A
The fans were well behaved and the game was played without _____.[ ]
A. action
B. accident
C. event
D. matter
3311E汽车转向系统中的储能器为（）式。
A.重锤
B.活塞
C.叶片
D.气囊
