流速是指液体质点在单位时间内运动的距离,流速的单位为()。
A.kg/m3
B.N/m2
C.m/s
D.m/s2
参考答案:C
ZhangHong appears _____ by heart 2000 words up to now.[ ]
A. to be learning
B. to have learned
C. to learn
D. having learned
如图所示,当开关S闭合时,两灯均发光,电流表A和A1比较, 的示数较大.滑片P向左移动时,电流表A的示数 (填“变大”、“不变”或“变小”).经过一段时间后有一盏灯熄灭,电流表A的示数变小,且滑片P无论怎样滑动,电流表A的示数都不发生变化,由此判断,电路的故障是 .