A.C20 B.C25 C.C30 D.C40
A.3% B.8% C.5% D.10%
A.冷拉、配料、對(duì)焊 B.冷拉、對(duì)焊、配料 C.配料、對(duì)焊、冷拉 D.配料、冷拉、對(duì)焊