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【简答题】
Today, bicycles are elegantly simple machines that are common around the world. Many people ride bicycles for recreation, whereas others use them as a means of transportation. The first bicycle was invented in Germany in 1818. Because it was made of wood, it wasn’t very strong nor did it have pedals (脚踏板).Riders moved it by pushing their feet against the ground. In 1839, Kirkpatrick Macmillan, a Scottish blacksmith, invented a much better bicycle. Macmillan’s machine had iron-covered wheels to keep them from getting worn down. He also used foot-operated levers, similar to pedals, so his bicycle could be ridden at a quick pace. It didn’t look much like the modem bicycle, though, because its back wheel was substantially larger than its front wheel. Although Macmillan’s bicycles could be ridden easily, they were never produced in large numbers. In 1861, Frenchman Pierre Michaux and his brother Ernest invented a bicycle with an improved pedal mechanism. They called their bicycle a velocipede,but most people called it a “bone shaker” because of the effect of the wood and iron frame. Despite the impolite nickname, the velocipede was a hit. After a few years, the Michaux family was making hundreds of the machines annually, mostly for fun-seeking young people. Ten years later, James Starley , an English inventor, made several innovations that revolutionized bicycle design. He made the front wheel many times larger than the back wheel, put a gear on the pedals to make the bicycle more efficient,and lightened the wheels by using wire spokes. Although this bicycle was much lighter and less tiring to ride, it was still clumsy, extremely top-heavy,and ridden mostly for entertainment. It wasn’t until 1874 that the first truly modern bicycle appeared on the scene. Invented by another Englishman, H. J. Lawson, the safety bicycle would look familiar to today’s cyclists. The safety bicycle had equal-sized wheels, which made it easier to ride. Lawson also attached a chain to the pedals to drive the back wheel. By 1893,the safety bicycle had been further improved with air-filled rubber tires, a diamond-shaped frame, and easy braking. With the improvements provided by Lawson ; bicycles became extremely popular and useful for transportation. Today, they are built, used, and enjoyed all over the world. 小题1:This passage was most likely written in order to _____. A.compare bicycles used for different purposes B.describe the problems early bicycle makers experienced C.persuade readers to use bicycles for transportation D.tell readers about the early history of the bicycle 小题2:Macmillan covered the wheels of his bicycle with iron to _____ A.add weight to the bicycle B.make the bicycle easier to ride C.allow the wheels to last longer D.let the bicycle be more comfortable 小题3:Which of the following bicycle types was invented by James Starley? 小题4:Which of the following statements is true according to the passage? A.Two hundred years ago,bicycles did not exist. B.The first bicycle could be ridden at a very quick pace. C.The Michaux brothers called their bicycle a “bone shaker”. D.Macmillan’s machine had wheels with rubber tires. 小题5:The information about bicycles in this passage is arranged according to _____. A.importance B.time C.place D.Interest
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【简答题】使放大器与信号源、负载之间的大小不同的 互相不产生干扰,但又能够把信号源提供的 传递给放大器,放大后的 再传递给负载,保证信号源、放大器、负载均能正常工作。
【判断题】The difference between FAS and FOB is that the seller delivers the goods alongside the ship under FAS, while FOB requires the seller to deliver the goods on board the vessel at port of shipment.
A.
正确
B.
错误
【判断题】( )企业往来结算款项主要包括应收款项、应付款项和预收、预付款项等。
A.
正确
B.
错误
【单选题】材料的最大工作应力σ max ,极限应力σ°及许用应力 [ σ ] 之间的关系是
A.
σ°≥ [ σ ] ﹥σ max
B.
σ°﹥ [ σ ] ≥σ max
C.
σ°﹥σ max ≤ [ σ ]
D.
σ°=σ max ≤ [ σ ]
【简答题】一个零件,已知其材料的 σ -1 =480MPa , φ σ =0.2 , σ s =800MPa ,若零件受单向稳定循环变应力作用,在危险剖面上作用的最大工作应力为 σ max =450MPa ,最小工作应力为 σ min = 150MPa ,危险剖面的 综合影响系数K σ = 1.5 ,应力变化规律为 r = 常数。要求: 1. 试按比例绘制此材料的简化极限应力简图; 2. 试按比例绘制此零件...
【简答题】某轴受弯曲稳定变应力作用。最大工作应力σ max =500MPa,最小工作应力σ min =200MPa。已知轴的材料为合金调质钢,其对称循环疲劳极限σ -1 =450MPa。脉动循环疲劳极限σ 0 =7000MPa,屈服极限σ S =800MPa。 试求: 1)绘制材料的简化极限应力图(每1mm代表10MPa), 2)按简单加载在图上表示出零件的工作应力点N和材料的强度极限点E, 3)计算材料强...
【简答题】小王所在城市最近发生了几起严重车祸,小王非常害怕,不敢独自过马路,担心汽车突然失控撞过来.社会工作者先与小王一起把他害怕的事情按害怕程度进行排序,然后从最轻度的开始做起,如果他仍然感到害怕,就做放松练习,小王对汽车的害怕程度逐渐减轻。上述过程中,社会工作者运用了()技巧。 A系统脱敏 B快速脱敏 C厌恶疗法 D果敢训练
【单选题】4G 网络使用的是 ( )
A.
宏基站
B.
微基站
C.
微微基站
D.
分布式基站
【判断题】Under FAS, the goods are delivered at theseller’s factory or warehouses ( )
A.
正确
B.
错误
【判断题】Under FAS and FOB terms, the buyer must pay the freight necessary to bring the goods to the named port of destination.
A.
正确
B.
错误
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