现代炼钢电弧炉的炉底时不导电的，电弧发生在每一个电极与金属炉料之间，以熔化的金属作为负荷的中型点。
参考答案：对
Eating carrots is good for our health. But I don't like them at all and I eat them. [ ]
A. always
B. sometimes
C. usually
D. never
肝海绵状血管瘤的推荐放疗剂量为()
A.30~40Gy
B.15~20Gy
C.20~30Gy
D.40~45Gy
E.45~50Gy
