新视通业务故障全程修复的时限要求为（）小时。
A.2
B.4
C.6
D.8
参考答案：B
John’s success has nothing to do with good luck. It is years of hard work _________has made him what
he is today. [ ]
A. why
B. when
C. when
D. that
防腐层电阻率是反映防腐层（）程度的指标。
A.防腐
B.绝缘
C.质量
D.厚度
