在北京,下列哪一选项是一年四季都能看到的星座?()
A、天琴座
B、狮子座
C、北冕座
D、小熊座
参考答案:D
TN系统用于配电变压器低压中性点()的配电系统。
A.经电抗器接地
B.经高阻抗接地
C.直接接地
D.不接地
The fire was finally_____ after the building had _____for two hours. [ ]
A. put off ; caught fire
B. put away; been on fire
C. put out ; been on fire
D. put out; caught fire