题目

两个电阻R1、R2的电流和电压的关系如图所示，可知两个电阻的阻值大小之比R1∶R2等于（     ）       A．1∶3      B．3∶1      C．1∶     D．∶1 答案：ASo absorbed     in the experiment that he didn’t even notice it was already over 12 o’clock.A．did heB．he didC．was heD．he was