强制动时,下列除了哪一项外均可能导致鼓式制动器效能衰退()
A.计量阀失效;
B.制动鼓不圆;
C.制动蹄发亮;
D.制动蹄安装有误。
参考答案:A
下列说法正确的是( )
A.布朗运动是液体分子的无规则运动的反映
B.分子势能随分子间距离的增大而增大
C.分子间相互作用的引力和斥力都随分子间距离的增大而减小
D.气体分子的平均动能越大,则气体压强越大
We were scared to death when the fire ____ . Fortunately, it was put out before it caused much
damage. [ ]
A. broke out
B. came out
C. gave out
D. turned out