As oil pipe line connections were broken,（

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问题单项选择题

As oil pipe line connections were broken,（）quantity of oil was caused to spill onto the wharf and into the dock water.

A.a not knowing

B.an unknowing

C.an unknown

D.a not known

答案

参考答案：C

问答题简答题

参加交易的买受人代表须交验哪些材料？

多项选择题

使用兆欧表时应注意下列哪些事项（）。

A.必须正确选用兆欧表；

B.连接导线必须用多股线，且在测量时相互连接；

C.每次使用前均需检查兆欧表是否完好；

D.只有在设备完全不带电的情况下才能用兆欧表测量绝缘电阻；

E.测量时兆欧表手柄转速应逐渐加快至额定转速，且只有在指针稳定不再摇摆后约1min读数。