单项选择题
A.1:2 B.1:3 C.1:2.5 D.1:5
A.10mm B.20mm C.40mm D.60mm
A.搭接焊、帮条焊、坡口焊 B.电渣压力焊、埋弧压力焊 C.对焊、点焊、电弧焊 D.电渣压力焊、埋弧压力焊、气压焊
A.3% B.4% C.5% D.5.5%
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