汽车起步时无异响,行驶中却有异响,为万向传动装臵()所致。
A.动不平衡
B.配合松旷
C.装配不当
D.动不平衡
参考答案:C
.--- What about listening to the English program on the radio while learning English?
--Personally,___________.
A.it’s up to you.
B.it makes sense.
C.it’s a shame.
D.it’s out of the question.
如图所示,测力计、绳子和滑轮的质量都不计,摩擦不计。物体A重40N,物体B重10N。以下说法正确的是
A.地面对A的支持力是30N
B.地面对A的支持力是20N
C.测力计示数20N
D.测力计示数30N