A:turned to
B:turned into
C:turned u
D:turned dow
è hào
yǒu yì
gē yáo
dà sǎo
gāng qiáng
____
物理兴趣小组的同学们想探究通过导体的电流与电压的关系.实验室有:电源、电压表、电流表、滑动变阻器、规格不同的定值电阻、开关和导线等器材各若干供同学们选择,实验用电路如图a所示.