题干

北京地铁S1线是北京市正在建设中的一条中低速磁悬浮轨道线.该线路连接北京城区与门头沟区,全长10.2km,计划2017年全线通车.列车通过磁体之间的相互作用,悬浮在轨道上方,大大减小了运行中的阻力,最高运行时速可达100km/h.图为磁悬浮列车悬浮原理的示意图,图中悬浮电磁铁与轨道电磁铁间的相互作用为

(   )

A:异名磁极相互吸引

B:同名磁极相互吸引

C:异名磁极相互排斥

D:同名磁极相互排斥

上一题 下一题 0.0难度 选择题 更新时间:2019-08-18 11:58:07

答案(点此获取答案解析)

D

同类题3

完形填空

    Powell was walking home one dark night. As he1the city bridge, he noticed something 2--a person was sitting on the rail, legs hanging over a3 about 100 feet below, at this time.

    “At first I thought he was just4 But as I got closer, I heard him whispering.5I clearly heard ‘I'm just going to jump,'” said Powell.

    “Hey, buddy, what are you doing?” Powell asked. He kept his6, standing about six feet away not to 7the guy.

    “I'm going to jump,” the guy said.

    “His8had pain in it, but I could9he didn't really want to do this. He10felt there wasn't any other way.” said Powell.

    Powell sought to11him. “You have any kids?”

    Without turning to look at Powell, the stranger only showed a12of his daughter on his cell phone. She looked to be two years old. “Think about how13her dad at a young age will affect her.” Powell14 Over the next ten minutes they talked, the stranger gradually opened his heart.

    “I'm having a15time.” the stranger said. “I can't make any money and I'm hungry.”

    Thankfully, Powell's calm, sincere persuasion caused the stranger to16turn and look at him. Powell, now about two feet from the stranger, held out his hand and17it there. “I felt I could catch him18if he jumped, but I also wanted him to know that I was there for him.” he said. To his19 the stranger took his hand and climbed down.

    Powell is great! It's always good to offer help and show your care if you find someone in your life20with disappointment.