什么叫碱性焊条?
参考答案:
焊条熔渣成分主要是碱性氧化物(如大理石、氟石等),并含有较多的铁合金,作为脱氧剂和合金剂,焊接时由大理石分解产生的二氧化碳作为保护气体。
—Bob speaks Chinese quite well.
—Yes, _____. Both of them practise ______ Chinese every day. [ ]
A. so does Tom, speaking
B. Tom does so, to speak
C. so Tom does, speaking
D. so does Tom, to speak.
直流电弧炉相比于交流电弧炉,其石墨电极消耗要()
A.低
B.高
C.差不多