问题
单项选择题
架空线路十字塔保护接地的接地电阻不宜大于()。
A.4Ω
B.5Ω
C.10Ω
D.30Ω
答案
参考答案:D
架空线路十字塔保护接地的接地电阻不宜大于()。
A.4Ω
B.5Ω
C.10Ω
D.30Ω
参考答案:D
阅读短文,然后在下面的表格中完成内容提要,每空不超过3个单词。(共4个小题,每小题2分) New Energy in the Twenty-first Century Energy from the wind Wind is a kind of clean energy, and there is lots of it, But, if there’s no wind, there is no wind energy. Energy from the water When water moves from a high place to a lower place, it can make electricity(电)without pollution. However, people have to build dams(水坝) to use this energy, and building dams is very expensive. Energy from the earth There is heat in the rocks under the earth. Scientists use the heat to make geothermal(地热的)energy. This kind of energy is cheap, but itis only possible in afew places in the world. Energy from the sun Solar panels (太阳电池板) on the roofs of houses can turn energy from the sun into electricity. Solar power is clean and plentiful(丰富的).but when the weather is bad, It doesn’t work. New Energy in Twenty-first Century
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