泄漏电流试验在高压电机、电缆、电容器等的预防性试验中被广泛采用。
参考答案：对
（1-x）4（1+x）4的展开式x2的系数是（ ）
A．-4
B．-6
C．6
D．4
—Shall we go out for a walk?
—Sorry. This is not the right ____ to invite me. I am too tired to walk.[ ]
A. moment
B. situation
C. place
D. chance
