血清钙降低可致（）
A.脐疝
B.方颅
C.手足搐搦
D.鸡胸
E.出牙延迟
参考答案：C
Now one of the most serious problems many people are worried about _____ on the lack of adequate housing
space. [ ]
A. insists
B. depends
C. agrees
D. focuses
分相绝缘器的爬电距离不应小于（）。
A、1200mm
B、1500mm
C、1600mm
D、1900mm
