问题
单项选择题
直流母线采用（）供电时，应采用（）的直流开关，分别带控制用负荷和保护用负荷。
A.双母线、相同位置
B.双母线、不同位置
C.单母线、相同位置
D.单母线、不同位置
答案
参考答案：D
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直流母线采用（）供电时，应采用（）的直流开关，分别带控制用负荷和保护用负荷。
A.双母线、相同位置
B.双母线、不同位置
C.单母线、相同位置
D.单母线、不同位置
参考答案：D
| 阅读短文，用方框中所给词的正确形式填空。 | |
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| There is something people didn't understand in the sky. The USAF (美国空军) 1 used the words"Unidentified Flying Object" to describe them. Today 2 uses the term UFO. When people see a UFO, it is 3 a weather balloon (气球) or an airplane. But the Center 4 UFO Studies continues to receive 5 of reports every year． In 1947 a businessman and pilot, Kenneth Arnold. 6 near Mount Rainier, Washington when he saw nine shiny, round objects flying through the air. He told a newspaper reporter that they 7 like "pie plates skipping over water". The reporter used the words "flying saucer" in his-story and today that 8 a popular name' for UFOs. Now in different countries, many people 9 the UFOs. Some people make mistakes when they say they have seen UFOs. But people still can't 10 UFOs clearly. It may take many years to find a clear answer. |