手工电弧焊时，当电弧的长度超过焊条焊芯直径时称为长弧；当电弧的长度小于焊条焊芯直径时称为短弧。
参考答案：对
____ could do such thing?
A．Whom do you think
B．Who do you think
C．Do you think whom
D．Did you think who
发病机制属于Ⅲ型超敏反应的疾病是
A．系统性红斑狼疮
B．链球菌感染后肾小球肾炎
C．肺出血肾炎综合征
D．Arthus反应
E．类风湿性关节炎
