钨极氩弧焊在大电流区间焊接时，静特性为（）
A.平特性区
B.上升特性区
C.陡降特性区
D.缓降特性区
参考答案：A
—Sandra failed to pass the exam.
— __________ ? Nobody works harder than she does.
A．How come
B．How about
C．Why not
D．What for
何谓潮汕“四点金”？
