下列哪种情况能产生HF有毒气体（）
A、手工电弧焊使用酸性焊条时
B、二氧化碳气体保护焊
C、手工电弧焊使用碱性低氢焊条时
参考答案：C
-What do you suppose her look so upset ?
- by her boyfriend again.
A．making; Misunderstood
B．made;Being misunderstood
C．has made;Be misunderstood
D．had nade; Having been nisunderstood
