题目

The man denied                           (偷窃了任何东西) at the supermarket before he was questioned by the police.(steal) 答案：having stolen anything  如图所示，MN间电压恒定，R1为定值电阻，滑动变阻器 R2的最大阻值为20Ω．当滑动变阻器滑片P处于a端时，电流表示数为 0.25A；当滑片P处于 ab 中点时，电流表示数为 0.40A，则 R1为3030Ω．