直流电动机启动时电枢电流较大的原因是（）。
A.启动时电枢反电动势最高
B.电枢反电动势最低
C.电枢回路电阻最小
D.电机励磁回路电阻最小
参考答案：B
Alice had a wonderful time yesterday, ______? [ ]
A. hadn't she
B. wasn't she
C. didn't she
D. wouldn't she
碳化塔内进行的总反应方程式是什么？
