Cars in America(美国的汽车)Cars in AmericaCars are an important part of lifein the United S The car made the UnitedStatesanationon Andit helped to make the United States what it is There are three main reasons why the car became so popular in the United S First of all the country is a huge one and Americans like to move around in The cars provide the most comfortable and cheapest form of The second reason that cars are popular is the fact that the United States never really developed an efficient and inexpensive form of public Long-distance trains have never been as common in the United States as they are in other parts of the Nowadays there is a good system of air service provided by But it is too expensive to be used The third reason is the most important one， The American spirit of independence is what really made cars Americans don't like to wait for a bus， or a train or even a They don't like to have to follow an exact And the freedom a car gives them is what Americans want most to The decrease of gas supplies has caused a big problem for A But the answer will not be a bigger system of public The real solution will have to be a new kind of car， one that does not use so much 美国的汽车汽车是美国生活的重要组成部分。汽车使得美国成为轮子上的国家，它也帮助美国成为现在的样子。汽车在美国如此盛行有三个主要原因。首先这个国家地域辽阔，而美国人喜欢在其间来回走动。汽车提供了最舒适最便宜的交通方式。汽车如此盛行的第二个原因是美国从未真正发展过有效廉价的公共交通这一事实。美国的长途火车从未像世界上其它地方那么普及。如今飞机提供了空中服务的良好体系。但是飞机太贵了，不能频繁使用。而第三个原因是最为重要的。美国人的独立精神是使得汽车盛行的真正原因。美国人不喜欢等公共汽车、火车甚至飞机。他们不喜欢必须遵循精确的时间表。汽车给予他们的自由正是美国人最想得到的。汽油供给的减少已经给美国人带来了巨大的问题。但答案不是发展更大型的公交体系。真正的解决方式必须是一种新型的汽车，那种不需要使用很多燃料的汽车。Car PollutionEach year there is an increasing number of cars on the roads as millions of new cars are One out of six Americans works at making cars， driving trucks， building roads or filling up Americans couldn't live without cars!Most Americans would find it hard to imagine life without a However， some have realized the serious problem of air pollution caused by The polluted air becomes poisonous and dangerous to One way to get rid of the polluted air is to make a car without But to build a clean car is easier said than Progress in this field is Another way is to replace car engines with something Inventors are now working on steam cars as well as electric Many makers believe that it will take years to develop a practical model for To prevent the world from being polluted by cars， we have to make some changes in our Americans， for example， have to cut down on the number of their total They are encouraged to use bicycles， which are thought to help keep the air But this change does not come A large number of workers may find themselves without jobs if a car factory cioses Thus the problem of air pollution would become less important than that of Although cars have led us to a better life， they have also brought us new 汽车污染上路的汽车数量逐年增长，同时，每年都会生产出几百万辆新车。在美国，每六个人中就有一个从事与汽车相关的工作：造车、开车、修路、加油等等。离开汽车，美国人无法生活!大部分美国人简直无法想象没有车的生活会是什么样子。但是一些人也已经意识到汽车造成的空气污染已成为严重的问题。被污染的空气具有毒性，并且危害健康。解决空气污染的方法之一就是制造无污染汽车。但是生产清洁汽车说来容易做来难。目前，这一领域的进展十分缓慢。另一个方法就是使用其他东西替代汽车发动机。发明家正在研制蒸汽汽车和电车。但是许多厂家认为我们可以使用的实用型汽车的诞生可能还需要几年时间。要想阻止全球化的汽车污染，我们需要对自己的生活方式做出适当的改变。例如，在美国，需要缩减汽车总量。鼓励人们使用有助空气清洁的自行车。但这种改变不能一蹴而就。一旦汽车工厂关闭，就会有大量工人失去工作。与失业相比，空气污染似乎就不再那么重要了。尽管汽车为我们带来了更加舒适的生活，同时，它也带来了新的问题。
Rear-end Collisions Rear-end Collisions， in which one vehicle runs into the back of another， can be treated in the same way as head-on collisions， except that the closing speed is the difference between the two speeds， and， while the occupants of the striking car suffer a frontal impact similar to that experienced in head-on collisions and tend to travel forward with respect to the car， those in the struck car tend to travel backwards relative to the car and therefore apply forces to the back of the Impacts with Walls In impacts of cars with walls， at all angles of approach( the angle between long axis of vehicle and wall) more than about 40°(see F1)， the impact is effectively a head-on collision， though less severe than impacts at angles approaching 90°， and the front-seat occupants move towards the The velocity of impact with the windscreen， steering assembly or instrument panel decreases as the angle of approach becomes smaller， but is greatly influenced by the coefficient of friction between the car and the wall; for example， when the coefficient changes from 25 to 5( approximately from a wooden surface to a concrete wall)， the impact velocities of the occupants on the interior of the car are approximately After impact the car may rotate towards or away from the wall-towards the wall if friction with the wall is low， and/or the angle of approach is small， and away from it when the friction is high， and/or the angle of approach is 4 Intersection Collisions Almost all intersection car collisions involve a striking and a struck The striking car suffers mainly frontal impact， and the struck car a side In most such accidents the paths of the two cars are at right angles， probably at a crossroads or T The struck car is usually moving more slowly than the striking In one investigation about 50 per cent of the struck cars were judged to be travelling at less than 2omile/h(32km/h)， and in about 60 percent the angles between colliding vehicles were about 90°。车尾碰撞 所谓车尾碰撞，即其中一辆车撞到另一辆车的车尾，可以用对待车头对撞一样的方式处理，除了闭合速度(好像是和排挡有关)是两者之间速度间的差别，同时碰撞的汽车驾驶者遭受正面撞击类似经历的正面碰撞的汽车，那些被困住的车会向后倒车，因此强加力于后座。 与墙体的影响 在汽车的影响与墙，在各个角度的办法（之间的夹角长轴车和墙）超过约40 ° （见F1 ）的影响，实际上是一个迎头相撞，但不是那么严重的影响角度接近90 ° ，和前座乘员朝着挡风玻璃。 速度的影响与挡风玻璃，方向盘组装或仪表板随角度的办法变小，但影响较大的摩擦系数之间的汽车和墙;例如，当变化系数从25到5 （大约从一个木制表面的混凝土墙） ，速度的影响的住户的室内汽车大约增加了一倍。 影响后车可旋转的或远离墙对墙摩擦，如果墙上低，和/或角的做法是小国，并远离它时，摩擦是很高，和/或角做法是大。 第4交叉口碰撞 几乎所有的汽车碰撞交汇涉及一个突出和一个击中汽车。汽车的罢工主要是受到锋面影响，并击中车侧的影响。在大多数这类事故的道路两辆赛车都成直角，可能在一个十字路口或Tjunction 。该组织通常是赛车运动更为缓慢的惊人车。在一个调查，百分之五十的击中汽车被认为是行驶不到2omile /小时（ 32公里每小时） ，并在大约百分之六十之间的角度相撞车辆约90 ° 。 语法绝对没问题的 谢谢采纳
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