| 电气化铁路的输电线常用图所示的方式悬挂在钢缆上．钢缆的A端固定在电杆上，B端连接在滑轮组上．滑轮组由a、b、c三个滑轮构成，配重P由多个混凝土圆盘悬挂在一起组成，配重的总重为G，若不计摩擦和滑轮的重量，则以下说法中正确的是（ ） A．a为动滑轮，B端钢缆受到滑轮组的拉力大小约为3G B．a为动滑轮，B端钢缆受到滑轮组的拉力大小约为 C．a、c为动滑轮，B端钢缆受到滑轮组的拉力大小约为3G D．a、c为动滑轮，B端钢缆受到滑轮组的拉力大小约为  |
答案：A
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| When I was in primary school, I got into a major argument with a boy in my class. I can't _1_ what it was about, but I have never forgotten the _2_ I learned that day. I was _3_ that I was right and he was wrong-and he was sure that I was wrong and he was right. The 4 decided to teach us a very important lesson. She 5 both of us up to the 6 of the class and 7 him on one side of her desk and me on 8 . In the middle of her desk was a large, round object. I could 9 see that it was black. She asked the boy what 10 the object was. "White," he answered. I couldn't believe he said the object was white, 11 it was obviously black! Another 12 started between my classmate and me, this 13 about the color of the object. The teacher told me to go to stand where the boy was standing and told him to come to stand where I had been. We changed 14 , and now she asked me what the color of the object was. I 15 answer, "White." It was an object with two 16 colored sides, and from his side it was white. 17 from my side was the color black. My teacher taught me a very important lesson that day: You must 18 in the other person's shoes and look at the 19 through their eyes in order to 20 understand their view. | ||||
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G
G