焊接电弧由哪几个区域组成?试述各区域的导电机构。 发布时间:2017-10-22 13:08 │ 来源:www.tikuol.com 题型:问答题 简答题 问题: 焊接电弧由哪几个区域组成?试述各区域的导电机构。
题型:问答题 简答题 4. Mr. Smith ______ that he had made a mistake and that he had corrected it.A.acceptedB.admittedC.talkedD.Promised 查看答案