简述自动重合闸的作用

A. found in the center(s) of the compass rose(s)
B. indicated by isogonic lines
C. found in a note on the chart
D. All of the above

A. 400微欧
B. 500微欧
C. 300微欧
D. 200微欧

A. 不需要
B. 必要的
C. 可做也可不做
D. 与环境因素和危害因素结合在一起做