进入轿厢顶时,首先切断轿厢顶上检修盒上的_,使电梯无法运行,再将有关开关置于检修状态。
参考答案:急停开关
Doing enough exercise _____ our health. [ ]
A. is good for
B. is good to
C. are good for
D. are good at
填料塔的作用原理如何?