A:boycott
B:contradict
C:finance
D:sponsor
There are not many cars on the road____ ____the bad weather.
用鱼缸养金鱼时,数量过多,就会出现金鱼频频浮头,并导致死亡,这是因为( )
如图所示,一质量不计的弹簧原长为10cm,一端固定于质量m=2kg的物体上,另一端施一水平拉力F.(设最大静摩擦力与滑动摩擦力相等,g=10m/s2,弹簧始终在弹性限度内)