单位面积上所受的压力，称为流体的压强。
参考答案：对
-- Hello, Maria! does Julia go to work every day?
-- She walks to the bus stop, then takes the bus.
A．How far
B．How long
C．How often
D．How
熔断器的电阻值（）。
A.很小
B.很大
C.相当于电阻元件
D.为0
