可靠性指标对不同的用户有不同的供电要求，一般分为三个等级。一级负荷的要求是( )。
A．供电中断将在政治上、经济上造成较大损失，或影响交通枢纽、通信设备正常工作，造成城市及重要公共场所秩序混乱
B．要求有两个独立的电源供电，一般采用出自不同变压器的两个独立电源供电
C．由两条线路供电，一条线路工作时，另一条线路处于备用或采用一条专用线供电
D．一般用单回线路供电
参考答案：B
| 完形填空。 | ||||
| A boy lost his arms in an accident and his father lost his life. Since then, he had to 1 the arms of his younger brother. Except for writing with his toes (脚趾头), he could hardly do 2 in his life. As the two brothers grew up together, they had lots of 3 and they often argued (争吵). Then one day, his younger brother 4 him. So he was very sad and didn't know 5 to do. A girl lost her hands because of a fire. Though her elder sister wanted to 6 her, she decided to be completely independent (独立的). At school, she always studied hard. Once she wrote the following in her composition,"I am 7 . Though I lost my hands, I still have legs. Though my wings are broken, my heart can still fly." One day, the boy and the girl were both invited 8 a television interview program. They both were asked to write something on a piece of paper with their toes. The boy wrote "My younger brother's arms are my arms" 9 the girl wrote "Broken wings, 10 heart". | ||||
|