A:Written, were
B:Written, there was
C:Writing, there was
D:Writing, were
关于曲线运动下列说法中正确的有( )
一只灯泡与变阻器串联后接在54伏的电源上,灯泡的额定电压是36伏,电阻是15欧,为使灯泡正常发光,此变阻器的规格应为( )
下列关于能量转化的实例,你认为说法正确的是( )