问题
单项选择题
低压供电系统中，采用多芯电缆总线作保护中性线（PEN线），其截面不应小于（）mm2。
A.4
B.6
C.10
D.16
答案
参考答案：A
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低压供电系统中，采用多芯电缆总线作保护中性线（PEN线），其截面不应小于（）mm2。
A.4
B.6
C.10
D.16
参考答案：A
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| Every year millions of people travel by plane without difficulty. I don't 1 very often, but I always seem to 2 into trouble. Trouble seems to like me; it goes with me 3 a friendly dog! Last year, for example, I wanted to come home 4 a winter vacation in Miami, Florida. I had to 5 a plane to Atlanta and then take another plane home. We left Miami on a Sunday morning. The 6 there was warm and sunny. We arrived in Atlanta at 12:30 p.m. but then it 7 to snow. In the next three hours,ten inches of snow fell. 8 the plane could not leave. After twenty-four hours at the Atlanta airport, I was able to 9 my journey! I arrived home and went to 10 . "You look tired," the people at work said. "You need a vacation!" This year I had to go to Washington D.C. for an important business meeting. 11 the plane journey, I wore sports clothes; they were old, but I felt 12 in them. My good clothes for the meeting were in my suitcase (手提箱). That was a very 13 idea! I 14 in Washington, but my suitcase didn't. Maybe it went to London or 15 to San Francisco, I didn't know, but it didn't arrive in Washington 16 me! I went to my important meeting 17 my tennis clothes. Now that is not a good way to 18 business! People in Washington wear suits to business meetings, not shorts and tennis shoes. My meeting did not 19 well. That was two weeks ago. Now I am home again, and I am 20 waiting for my suitcase. | ||||
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