题目内容

用直流电压表鉴别焊机正、负极。鉴别时将直流电压表的正、负极分别接在直流电源的两个电极上，若电压表指针向正方向偏转时，则与电压表正接相连接的焊机输出端是负极。( )

A. 对
B. 错

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焊接打底层焊道时，为了保证焊透，焊接电流要大些。( )

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