单项选择题
A.20m B.30m C.50m D.100m
A.水平距离 B.竖直距离 C.左边 D.右边
A.1:500 B.1:1000 C.1:2000 D.1:10000
A.—0.0025m B.-0.0025m C.>0.0025m D.<0.0025m
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