气体保护电弧焊所需电压与焊条电弧焊相比，（）。
A.高
B.低
C.相等
参考答案：A
24.The students were ____ over the ____ problem, listening to the teacher with a ____ expression on their faces.
A．puzzled; puzzling; puzzling
B．puzzled; puzzling; puzzled
C．puzzling; puzzling; puzzled
D．puzzling; puzzled; puzzling
扬基债券是欧洲债券的一种。（）
