15000 bài tập tách từ đề thi thử môn Tiếng Anh có đáp án (Phần 65)

Forces other than damaging winds are also at work inside tornadoes. Sometimes, as the writhing, twisting funnel passes over a house, the walls and ceiling burst apart as if a bomb had gone off inside. This explosion is caused by the low air pressure at the center of a tornado.

The pressure at the center of a tornado is usually 13 pounds per square inch. However, inside the house, the air pressure is normal, about 15 pounds per square inch. The difference of 2 pounds per square inch between the inside and outside pressure may not seem like much. But suppose a tornado funnel passes over a small building that measures 20 by 10 by 10 feet. On each square inch of the building, there is 2 pounds of pressure from the inside that is not balanced by air pressure outside the building. On the ceiling, that adds up to an unbalanced pressure of 57, 600 pounds. The pressure on the four walls adds up to 172,800 pounds.

If windows are open in the building, some of the inside air will rush out through them. This will balance the pressure inside and outside the building. But if the windows are shut tightly, the enormous inside pressure may cause the building to burst.

Unfortunately, heavy rain and hail often occur in thunderstorms that later produce tornadoes. So people frequently shut all windows to protect their property. This may cause far worse damage later. For the same reason, tornado cellars must have an air vent. Otherwise, the cellar door might be blown out when a tornado passes over it.

Native Americans from the southeastern part of what is now the United States believed that the universe in which they lived was made up of three separate, but related, worlds, the Upper World, the Lower World, and This World. In the last there lived humans, most animals, and all plants.

This World, a round island resting on the surface of waters, was suspended from the sky by four cords attached to the island at the four cardinal 'points of the compass. Lines drawn to connect the opposite points of the compass, from north to south and from east to west, intersected. This World to divide it into four wedge - shaped segments. Thus a symbolic representation of the human world was a cross within a circle, the cross representing the intersecting lines and the circle the shape of  This World.

Each segment of  This World was identified by  its own color. According to Cherokee doctrine, east was associated with the color red  because it was the direction of the  Sun, the greatest deity of all. Red was also the color of fire, believed to be directly connected with the Sun, with blood, and therefore with life. Finally, red was the color of success. The west was the Moon segment; it provided no warmth and was not life - giving as the Sun was. So its color was black. North was the direction of cold, and so its color was blue sometimes purple, and it represented trouble and defeat. South was the direction of warmth, its color, white, was associated with peace and happiness.

The southeastern Native Americans' universe was one in which opposites were constantly at war with each other, red against black, blue against white. This World hovered somewhere between  the perfect order and  predictability of the Upper World and the total disorder and instability of the Lower World. The goal was to find some kind of halfway path, or balance, between those other worlds.

Arid regions in the southwestern United States have become increasingly inviting playgrounds for the growing number of recreation seekers who own vehicles such as motorcycles or powered trail bikes and indulge in hill-climbing contests or in carving new trails in the desert. But recent scientific studies show that these off-road vehicles can cause damage to desert landscapes that has long-range effects on the area’s water-conserving characteristics and on the entire ecology, both plant and animal. Research by scientists in the western Mojave Desert in California revealed that the compaction of the sandy arid soil resulting from the passage of just one motorcycle markedly reduced the infiltration ability of the soil and created a stream of rain runoff water that eroded the hillside surface. In addition, the researchers discovered that the soil compaction caused by the off-road vehicles often killed native plant species and resulted in the invasion of different plant species within a few years. The native perennial species required many more years before they showed signs of returning. The scientists calculated that roughly a century would be required for the infiltration capacity of the Mojave soil to be restored after being compacted by vehicles.

Another critical factor that plays a part in susceptibility to colds is age. A study done by the University of Michigan School of Public Health revealed particulars that seem to hold true for the general population. Infants are the most cold-ridden group, averaging more than six colds in their first year. Boys have more colds than girls up to age three. After the age of three, girls are more susceptible than boy's , and teenege girls average three colds a year to boy’s two.

The general incidence of continues to decline into maturity. Elderly people who are in good health have as few as one or two colds annually. One exception is founds among people in the twenties, especially women, who show a rise in cold infections, because people in this age group are most likely to have young children. Adults who delay having children until thirties forties experience the same sudden increase in cold infections.

The study also found that economics play an important role. As income increases, the frequency at which are reported in the family decreases. Families with the lowest income suffer about a third more colds than families at the lower end. Lower income generally forces people to live in more cramped quarters than those typically occupied by wealthier by wealthier people, and crowding increases the opportunities for the cold virus to travel from person to person. Low income may also adversely influence diet. The degree to which poor nutrition affects susceptibility to colds is not yet clearly established, but an inadequate diet is suspected of lowering resistance

A number of factors  related  to the voice  reveal  the personality of the speaker.The first is the broad area of communication, which includes imparting information by use of language, communicating with a group or an individual and specialized communication through performance. A person conveys thoughts and ideas through choice of words, by a tone of voice that is pleasant or unpleasant, gentle or harsh, by the rhythm that is inherent within the language itself, and by speech rhythms that are flowing and regular or uneven and hesitant, and finally, by the pitch and melody of the utterance. When speaking before a group, a person's tone may indicate uncertainty or fright, confidence or calm. At interpersonal levels, the tone may reflect ideas and feelings over and above the words chosen, or may belie them. Here, the participant’s tone can consciously or unconsciously reflect intuitive sympathy or antipathy, lack of concern or interest, fatigue, anxiety, enthusiasm or excitement, all of which are .usually discernible by the acute listener. Public performance is a manner of communication that is highly specialized with its own techniques for obtaining effects by voice and /or gesture. The motivation derived from the text, and in the case of singing, the music, in combination with the performer's skills, personality, and ability to create empathy will determine the success of artistic, political, or pedagogic communication.

Second, the voice gives psychological clues to a person's self-image, perception of others, and emotional health. Self-image can be indicated by a tone of voice that is confident, pretentious, shy, aggressive, outgoing, or exuberant, to name only a few personality traits. Also the sound may give a clue to the facade or mask of that person, for example, a shy person hiding behind an overconfident front.

 How a speaker perceives the listener's receptiveness, interest, or sympathy in any given conversation can drastically alter the tone of presentation, by encouraging or discouraging the speaker. Emotional health is evidenced in the voice by free and melodic sounds of the happy, by constricted and harsh sound of the angry, and by dull and lethargic qualities of the depressed.

It is commonly believed that school is  where people go to get an education. Nevertheless, it has been said that today children interrupt their education  to go to school. The difference between schooling and education implied by this remark is important.

Education is much more open-ended and all-inclusive than schooling. Education knows no limits. It can take place anywhere, whether  in the shower or on the job, whether in the kitchen or on a tractor. It includes both the formal learning that takes place in school and the whole universe of informal learning. The agent (doer) of education can vary from respected grandparents to the people arguing about politics on the radio, from a child to a famous scientist.  Whereas schooling has a certain predictability, education quite often produces surprises. A chance conversation with a stranger may lead a person to discover how little is known of other religions. People receive education from infancy on. Education, then, is very broad, inclusive term; it is a lifelong process, a process that starts long before the start of school, and one that should be a necessary part of one’s entire life.

Schooling, on the other hand, is a specific, formalized process, whose general pattern varies little from one setting to the next. Throughout a country, children arrive at school at about the same time, take the assigned seats, are taught by an adult, use similar textbooks, do homework, take exams, and so on. The pieces of reality that are to be learned, whether they are the alphabet or an understanding of the workings of governments, have been limited by the subjects being taught. For example, high school students know that they are not likely to find out in their classes the truth about political problems in their society or what the newest filmmakers are experimenting with. There are clear and  undoubted conditions surrounding the formalized process of schooling.

The three phases of human memory are the sensory memory, the short-term memory, and the long- term memory. This devision of the memory into phases is based on the length of time of the memory.

Sensory memory is instantaneous memory. It is an image or memory that enters your mind only for a short period of time; it comes and goes in under a second. The memory will not last longer than that unless the information enters the short-term memory.

Information can be held in the short-term memory for about twenty seconds or as long as you are actively using it. If you repeat a fact to yourself, that fact will stay in your short-term memory as long as you keeprepeating it. Once you stop repeating it, either it is forgotten or it moves into long term memory.

Long-term memory is the huge memory tank that can hold ideas and images for years and years. Information can be added to your long-term memory when you actively try to put it there through memorization or when an idea or image enters your mind on its own.

Telecommuting is some form of computer communication between employees’ homes and offices. For employees whose job involve sitting at a terminal or word processor entering data or typing reports, the location of the computer is of no consequence. If the machine can communicate over telephone lines, when the work is completed, employees can dial the office computer and transmit the material to their employers. A recent survey in USA Today estimates that there are approximately 8,7 million telecommuters. But although the numbers are rising annually, the trend does not appear to be as significant as predicted when Business Week published “The Portable Executive” as its cover story a few years ago. Why hasn’t telecommuting become more popular?

Clearly, change simply takes time. But in addition, there has been active resistance on the part of many managers. These executives claim that supervising the telecommuters in a large work force scattered across the country would be too difficult, or, at least, systems for managing them are not yet developed, thereby complicating the manager’s responsibilities.

It is also true that employees who are given the option of telecommuting are reluctant to accept the opportunity. Most people feel that they need regular interaction with a group, and many are concerned that they will not have the same consideration for advancement if they are not more visible in the office setting. Some people feel that even when a space in their homes is set aside as a work area, they never really get away from the office.

FAMILY LIFE IN THE UNITED STATES

Family life in the United States is changing. Fifty or sixty years ago, the wife was called a “housewife”. She cleaned, cooked, and cared for the children. The husband earned the money for the family. He was usually out working all day. He came home tired in the evening, so he did not do much housework. And he did not see the children very much, except on weekends.

These days, however, more and more women work outside the home. They cannot stay with the children all day. They, too, come home tired in the evening. They do not want to spend the evening cooking dinner and cleaning up. They do not have time to clean the house and do the laundry. So who is going to do the housework now? Who is going to take care of the children?

Many families solve the problem of housework by sharing it. In these families, the husband and wife agree to do different jobs around the house, or they take turns doing each job. For example, the husband always cooks dinner and the wife always does the laundry. Or the wife cooks dinner on some nights and the husband cooks dinner on other nights.

Then there is the question of the children. In the past, many families got help with child care from grandparents. Now families usually do not live near their relatives. The grandparents are often too far away to help in a regular way. More often, parents have to pay for child care help. The help may be a babysitter or a day-care center. The problem with t his kind of help is the high cost. It is possible only for couples with jobs that pay well.

Parents may get another kind of help form the companies they work for. Many companies now let people with children work part-time. That way, parents can spend mo re time with their children. Some husbands may even stop working for a while to stay with the children. For these men there is a new word: they are called “househusbands”. In the USA more and more men are becoming househusbands every year.

These changes in the home mean changes in the family. Fathers can learn to understand their children better, and the children can get to know their fathers better. Husbands and wives may also find changes in their marriage. They, too, may have a better understanding of each other.

Because writing has become so important in our culture, we sometimes think of it as more real than speech. A little thought, however, will show w hy speech is primary and writing secondary to language. Human beings have been writing (as far as we can tell from surviving evidence) for at least 5000 years; but they have been talking for much longer, doubtless ever since there have been human beings.

When writing did develop, it was derived from and represented speech, although imperfectly. Even today there are spoken languages that have no written form. Furthermore, we all learn to talk well before we learn to write; any human child who is not severely handicapped physically or mentally will learn to talk: a normal human being cannot be prevented from doing so. On the other hand, it takes a special effort to learn to write. In the past many intelligent and useful members of society did not acquire the skill, and even today many who speak languages with writing systems never learn to read or write, while some who learn the rudiments of those skills do so only imperfectly.

To affirm the primacy of speech over writing is not, however, to disparage the latter. One advantage writing has over speech is that it is more permanent and makes possible the records that any civilization must have. Thus, if speaking makes us human, writing makes us civilized.