变配电所高压开关柜的操作机构一般采用（）操作机构。
参考答案：直流电磁
The earthquake which happened in Yushu 14th April 2010 was a big disaster. [ ]
A. at
B. on
C. in
D. to
国家标准用汉语拼音字母（）表示。
A．GB
B．YB
C．Gb
