在雷暴日多的地区，应增长接地装置的间距或改善屏蔽层接地装置的接地电阻，以提高防雷效果。。
参考答案：错
— I was told to be here at this time.
— Sorry, you ______. I forgot to tell you we've changed the plan. [ ]
A. must
B. may
C. can't
D. needn't
注浆压力允许偏差为（）%。
A、±10
B、±20
C、±30
