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A Train Floating On Air A train that floats on air? It's not magic―it's magnets (磁).And it's close to reality. In Virginia USA the fall of 2002, a train with no wheels traveled on air and carried college students across their campus.In Japan, a whisper-quiet railway engine hovered and raced at 350 miles per hour using magnets and electricity as the power.And in China, a magnet train line linked Shanghai with nearby Pudong Airport. These trains use magnetic levitation (悬浮) technology, “maglev” for short. They use the same rules as the magnets you pick up at home or school: opposite poles of magnets attract each other, and like poles repel each other. How does it work? Powerful magnets on the bottom of the train repel magnets on the track, which is actually just a magnet-filled guiding way. With a magnetic field of sufficient force, the train will go hovering on air, which seemed impossible to us in the past. When an electrical current is sent through the track, the train moves. Turn the current backwards and the train slows down. Maglev doesn't rely on the friction (摩擦力) of wheels on track, so it can climb a much steeper hill than a traditional train. And it can travel easily in snow and ice, something that could bring normal trains to a screaming stop. 小题1:This passage is about __________. A.maglev B.magnets C.levitation D.electricity 小题2: Which of the following is a repelling action? A. B. C. D. 小题3:What can we learn from the text? A.A magnet-filled guiding way is formed inside a maglev train. B.Instead of electricity, magnets are used as the power of a maglev. C.Maglev trains can climb hills with the help of magnetwheels. D.Electric currents decide the movements of a maglev train. 小题4: What is the difference between a maglev train and an ordinary train? A.A maglev train can climb mountains without power while an ordinary o ne can’t. B.A maglev train can travel in college campus while an ordinary train is not allowed. C.Travelling without a track, a maglev train is safer and smoother than an ordinary one. D.Floating on a track, a maglev train is faster, quieter than an ordinary railway train.
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举一反三
【多选题】下列哪项不是肝硬化特征性病理表现
A.
肝细胞坏死
B.
假小叶形成
C.
炎细胞浸润
D.
正常肝小叶
E.
肝内循环紊乱
【多选题】班轮运费里包括( )
A.
装卸费
B.
油费
C.
超长附加费
D.
港口选择费
【简答题】1985年前,某地农村农作物秸秆都是当作燃料而农户和家畜的粪便等均作为肥料直接施入农田。后来逐步开始进行农村产业结构调整,下图是2006年时当地生态工程示意图。 (1)试分析1985年前生产形式的不利影响(至少举两个方面)__________。 (2)该生态工程的建设遵循了__________等基本原理。生态工程与传统工程相比较,具有____________等特点。 (3)当地人希望进一步提高该系...
【判断题】程租船的装卸费用如果采用“班轮条款”,则是由承租人负责承担装船费和卸船费。不包括在程租船的运费里面。
A.
正确
B.
错误
【多选题】农田整地的主要作用有:
A.
掩埋前作物残茬和表面的肥料,为播种提供良好的苗床
B.
为作物生长发育提供适宜的土壤表面和良好的耕层结构
C.
防除、抑制杂草和病虫害
D.
熟化土壤和保蓄水分
【单选题】如图 山东半岛蓬莱登州沿岸水下 Zm 深处有一片浅滩沙坝,沿岸的村庄自建村以来,从未受过海浪威胁。自 1985 年以来,为整治航道不断开挖水下浅滩, 1 990 年发生了两次大风浪,造成海岸线后退,并冲毁民房和农田。据此完成 6 — 8 题。 该区域浅滩沙坝形成的主要地质作用为
A.
河流沉积
B.
海浪沉积
C.
风力沉积
D.
冰川沉积
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【多选题】现代构成设计作为现代设计理念产生于20世纪20年代,其构成主义理论体系主要是受( )、( )、( )等方面的影响。
A.
俄国构成主义
B.
荷兰风格派
C.
包豪斯设计学院
D.
装饰主义运动
【简答题】编写一函数reverse实现一个字符串按反序存放,要求在主函数main中输入字符串,并输出反序后的字符串。不能使用strlen库函数。      例如:输入string,则输出gnirts。
【单选题】三相电源绕组的首尾顺序相连的连接方式称为
A.
三角形连接
B.
星形( Y形)连接
C.
短接
D.
对称型
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