题目

Tom told us all that ____ he said so at the meeting was really true. A. what                             B. that                       C. which                    D. all that 答案：B19．如图所示，电源电压恒定，小灯泡L标有“3V 0.6A”字样，R为定值电阻，闭合开关S，断开开关S1，小灯泡正常发光；若再闭合开关S1，发现电流表示数变化了0.3A，则R的阻值为10Ω，此时灯泡L和电阻R消耗的电功率之比是2：1．