题目

Determined not to fall behind, Alex now spends ________ as he used to on physics, his weakest subject. A . twice as much time B . as twice much time C . twice much time as D . as twice time much 答案：A将两个电源先后接入测定电源电动势和内电阻的电路中，测得的U-I图线如图所示，由图线可知（　　）A．ε1=ε2，r1＞r2B．ε1=ε2，短路电流I1＞I2C．发生相同电流变化时，电源1的路端电压变化大D．在发生相同电流变化时，电源2的路端电压变化大