2012年12月英语四级考试考前预测试卷

　　23. Questions 1~5are based on the following passage.

　　Over the last 25 years, British society has changed a great deal--or at least many parts of it have. In some ways, however, very little has changed, particularly where attitudes are concerned. Ideas about social class--whether a person is "working- class" or "middle-class"--are one area in which changes have been extremely slow.

　　In the past, the working-class tended to be paid less than middle-class people, such as teachers and doctors. As a result of this and also of the fact that workers' jobs were generally much less secure, distinct differences in life-styles and attitudes came into existence. The typical working man would collect his wages on Friday evening and then, it was widely believed, having given his wife her "housekeeping", would go out and squander(浪费) the rest on beer and betting.

　　The stereotype ( 陈腔滥调) of what a middle-class man did with his money was perhaps nearer the truth. He was—and still is--inclined to take a longer-term view. Not only did he regard buying a house of these provided him and his family with security. Only in very few cases did workers have the opportunity (or the education and training) to make such long-term plans.

　　Nowadays, a great deal has changed. In a large number of cases factory workers earn as much, if not more, than their middle-class supervisors. Social security and laws to improve century, have made it less necessary than before to worry about "tomorrow". Working-class people seem slowly to be losing the feeling of inferiority they had in the past. In fact there has been a growing tendency in the past few years for the middle-classes to feel slightly ashamed(惭愧的)of their position.

　　The changes in both life-styles and attitudes are probably most easily seen amongst younger people. They generally tend to share very similar tastes in music and clothes, they spend their money in having a good time, and save for holidays or longer-term plans when necessary. There seems to be much less difference than in precious generations. Nevertheless, we still have a wide gap between the well-paid (whatever the type of job they may have and the low-paid. As long as this gap exists, there will always be a possibility that new conflicts and jealousies will emerge, or rather that the old conflicts will re-appear,but between different groups.

　　24. Questions1~5are based on the following passage.

　　If a mother pushes her small son in a swing (秋千), giving only a light force each time he returns, eventually he will be swinging quite high. The child can do this for himself by using his legs to increase the motion, but both the mother's push and the child's leg movements must occur at the proper moment, or the extent of the swing will not increase. In physics, increasing the swing is increasing the amplitude ( 振幅 ); the length of the rope on the swing determines its natural oscillation ( 摆动 ) period. This ability of an object to move periodically or to vibrate when stimulated by a force operating in its natural period is called resonance.

　　Resonance is observed many times without consciously thinking about it; for example, one may find an annoying vibration or shimmy in an automobile, caused by a loose engine mount vibrating with increasing amplitude because of an out- of-round tire. The bulge ( 凸出部分) on the tire slaps the pavement with each revolution; at the natural resonance point of the engine mount, it will begin to vibrate. Such vibrations can result in considerable damage if allowed to persist. Another destructive example of resonance is the shattering of a crystal goblet by the production of a musical tone at the natural resonant point of the goblet. The energy of the sound waves causes vibration in the glass; as its amplitude increases, the motion in the glass exceeds the elasticity of the goblet, and it shatters.

　　An instrument called a tachometer (转速计) makes use of the principle of resonance. It consists of many tiny bars, loosely fastened together and arranged so that each bar can slide independently of the others. Movement of the bars causes changes in a dial. When placed next to a rotating motor or engine, the tachometer picks up slight vibrations which are transferred to the resonant bars. These bars begin to move, and the resulting dial may be read to find the revolutions per minute of the motor very quickly.

　　完形填空

　　1. PartIV Cloze(15 minutes)

　　An adult giraffe's head is about six feet above its heart. This means that to 67 enough blood up to the brain the circulatory 68 must be strong enough to keep the blood at very high pressure.

　　Biologists have known for some time that giraffes solve this problem by having 69 high blood pressure, about 70 that of human beings. But an international team of biologists began to 71 about this. If giraffes have such high blood pressure, they should have a 72 problem with swelling in their legs and feet. Why don't giraffes

　　have swollen feet?

　　Giraffes should have 73 problem, too. Every time they bend heads __7_4__ to drink, the blood should 75 to their heads and have a hard time 76 back up (when the head is down) to the heart. How come giraffes don't black out when they drink?

　　The answer to the 77 feet problem, the researchers found, is that giraffes have 78 the researchers call a "natural anti-gravity suit". It 79 out that the skin

　　and other 80 in their legs and feet are 81 stiffer and tougher than those of other 82 . As a result, the blood vessels in the leg cannot swell.

　　Therefore, the blood has nowhere to go but back to the heart. What about blood rushing to the head 83 the giraffe bends down to drink? The researchers found that the giraffe's jugular vein, which 84 blood from the head back to the heart, has lots of one-way valves in it. In the giraffe's neck, there are lots of muscles that flex and relax repeatedly as the animal moves its head and sucks 85 drinking water. By squeezing the valved jugular vein, they 86 blood moving back to the heart even while the animal is drinking.

　　阅读以上文章，回答1~20题

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