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_爱下问搜题

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问题选择题

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G

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G

答案

答案：A

完形填空

通读下面短文，掌握其大意，然后在各题所给的A，B，C，D四个选项中，选出一个最佳答案。
As I had my first child, I promised myself never to be a pushy parent. I was going to be a very 36 and understanding mother.
Five years later my little boy was about to 37 for his yellow belt in karate(空手道). As a five-year-old child, he wasn’t taking it 38 , because it was Mom trying to help him. I found myself yelling and telling him he would never get the belt acting like that. I was trying to 39 him his back-flip（背摔）. He continued to play and I continued to 40 . Finally I had made him feel like he couldn’t 41 anything, just as I promised myself I wouldn’t do.
Still mad and stubborn I couldn’t 42 . I had to teach him his flip. He was doing fine with it by the time we had to leave to go to karate. While taking the test, he did 43 . His instructor would ask him to do something, and it became 44 for him. He never asked him to do the back-flip. He had passed his yellow belt test.
We got in the car to 45 when he looked at me and said ”Mom, why did you make me do that back-flip so many times, 46 it wasn’t even on the test.” The words wouldn’t have 47 anything to anyone else, but it was a slap in my face. That night while 48 in bed, I told him I loved him.
He was 49 and didn’t say anything, just giggled. I said “I really do love you baby.” I was still feeling 50 , and also wondering if he had 51 me. Finally he replied in the 52 voice, “I know you do, but I love you more.”
He had forgiven me and I had decided that his feeling were more 53 than any test he would 54 take. I made a new 55 to be better mother and to accept that he was only a child.

D．affectionate

A．go shopping

C．rest ourselves

D．enjoy ourselves

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单项选择题

中国工会具有鲜明的阶级性、高度的政治性、（）。

A.广泛的群众性

B.科学性

C.维护性