低压主干线路在发生撞杆事故时，在处理前应采取（）等措施。
A.巡查
B.停电
C.隔离
D.支撑
参考答案：B, C, D
在海洋中生活的鲸，它的体温是恒定的，而鲨鱼的体温是随海水的温度而变化的．______．
--- Why did you laugh just now?
--- John wanted to tell us very funny joke, but he forgot end himself.
A．/; the
B．a; an
C．a; the
D．the; the
