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当前学科:燃气具安装维修工考试
题目:
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封堵作业坑底最小宽度W与管道外径D之间的关系是()。
A . A、W=D+2.0
B . B、W=D-2.0
C . C、W=D*2.0
D . D、W=D/2.0
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