低压熔断其主要由（）组成。
A、熔管
B、金属熔管
C、触头座
D、固定触头座
参考答案：A, B, D
Having completed our adventurous journey through the forest, we went back to our camping site, ____. [ ]
A. exhaustedly but excitedly
B. exhaustedly but excited
C. exhausted but excitedly
D. exhausted but excited
不适合电子商务的业务是（）
A.出版业务
B.软件、音像制品的购销
C.旅游服务的促销
D.时装和易腐食品的购销
