铅套管电缆直通头接续时，7x4电缆甲端电缆外护套到已端电缆外护套距离是（）。
A.530mm
B.540mm
C.550mm
D.560mm
参考答案：D
.---I didn't go to work yesterday because my car broke down.
---You ____ mine. I wasn't using it then.
A．might borrow
B．could have borrowed
C．must have borrowed
D．ought to borrow
安装补偿导线时，周围温度不应超过（）。
A、80℃
B、100℃
C、60℃
D、200℃
