题目

I don’t mind picking up your things from the store. _____, the walk will do me good. A. Sooner or later             B. Still                  C. Besides                    D. In time  答案：C电灯的电阻为30W，正常发光时通过它的电流为0.1A，现把它接在恒定电流为0.4A的电路中，要使它正常发光，应把________W的电阻跟电灯________联，此时电阻消耗的电功率是________W。