Force other than damaging winds are also at work inside tornadoes. Sometimes, as the turning, jumping funnel(漏斗) passes over a house, the walls and ceiling burst apart as if a bomb had gone off inside. This explosion(爆炸) 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 great inside pressure may cause the building to burst.
Unfortunately, heavy rain happens in thunderstorms that later produce tornadoes. So, people often shut all windows to protect their property. This may cause far worse damage later.
63. Which of the following is the main topic of the passage?
A. Where tornadoes are formed. B. When tornadoes usually occur.
C. How tornadoes can be prevented. D. Why tornadoes cause so much damage.
64. According to the passage, tornadoes can destroy building because the _____.
A. force of a tornado increases the air pressure in a building
B. air pressure at the center of a tornado is over 172,000 pounds
C. weight of a tornado can crush a building’s roof when it passes overhead
D. air pressure inside a tornado is less than the air pressure inside a building
65. According to the passage, the pressure on a building during a tornado can be reduced by _____.
A. closing the windows B. opening the windows
C. using an electric fan D. making the roof and walls stronger
Like all other mothers who have small children, I, too, have to steal time-from my own children at home and from the children who know me as their teacher-just to put a few words down on paper. Many times I’ve wanted to write for myself, for other women, for my parents, for my husband, and especially for my children. I would have liked to leave a legacy (遗产) of words explaining what it has meant to have twins. One reason that there is not a great deal written about being a mother of a new baby is that there is seldom a moment to think of anything else but the baby’s needs.
With twins, I did not have a spare hand to write with.
Before my twins were born, my days were long and I had nothing to write about. After the twins’ birth I did have something to write about, but I found myself facing not a pen and paper but milk bottles.
Some nights, friends would visit. They would leave at 11 p.m., heading for bed, and for us the night was only just beginning. With twins, there is really no night. Each feeding lasts a long time. At 1:00 a.m., each of them would begin crying from hunger. At 4:00am, when I finally put them down, I felt exhausted.
Two years have passed since then and we’ve managed to live through it all. My days are still very full and even now there isn’t one evening when I put the twins down for the night that I don’t have a break. At last a little time for myself.When did the writer have time but she didn’t feel like writing anything?
| A．Before the birth of her twins. |
| B．When she faced bottles of milk. |
| C．After her friends visited her home. |
| D．When she had to think about the babies’ needs. |
What does the writer mainly write about?
| A．Her role as a wife. | B．Her work as a writer. |
| C．Her experience as a mother. | D．Her feeling as a woman. |
Why did the writer say the night was just beginning (in the 4th paragraph)?
| A．Because her friends left her house too late. |
| B．Because she started to take care of the twins even at night. |
| C．Because her babies often cried and she woke up. |
| D．Because she could not sleep till four in the morning. |
This passage is probably from a(n) _________.
| A．blog | B．newspaper | C．guidebook | D．advertisement |
What can we learn from the passage?
| A．The writer was unhappy because of no time for writing. |
| B．The writer cared about her babies more than her own interests. |
| C．The writer hated to be a mother of twins. |
| D．The writer could steal a little time at night. |
You probably know you should say “please” and “thank you” at restaurants. You probably know the rules of a library. You know you should respect and be nice to your classmates. But do you have music manners?
Keep It Down! You have to notice the volume of your music. You should not play your music so loud that everyone around you can hear it. Some people might even get angry. Usually, when you play the music loud on an MP3 player, other people can’t hear the words of the song. They just hear a loud sound. No one wants to listen to this. Very loud music can also be bad for your ears. So even if you are alone when listening to our MP3 players, you shouldn’t turn it up too high.
Take Them Off! You need to know when to turn your MP3 off and put it away. Libraries, and schools don’t allow MP3 players. There are other places, like museums, that don’t have rules, but it would be rude to have your MP3 player on. Sometimes, it doesn’t make sense to listen on your MP3 player at event. Why would you listen to music at a play, a movie or a sporting event? You would miss what is going on and others would wonder why you even came.
Take One Out! Once in a while it’s okay just to take out one earphone and not other. Imagine you are listening on your MP3 player when someone asks you the way. It would not be rude to take out one earphone, tell him the way, and put back the earphone and continue listening. You can also do this when you order food at a fast-food restaurant or when you answer 
the telephone and it’s not for you.
It’s Your Choice! There are times when you need to decide what is best. F
or example, some people can listen to music on their MP3 players when reading books, while others think it is disturbing. In cases like this, you need to do what seems right for you.The underlined word “volume” in Paragraph Two probably means “_________.”
| A．the type of music | B．the amount of a sound |
| C．the length of a song | D．the colour of an MP3 player |
No one wants to listen to_________from others’ MP3 players.
A. a loud sound B. sad stories
C. a long movie D. the words of a song
43. We should turn down the mu
sic when we are alone because loud music_________.
A. is not enjoyable B. makes us tired
C. is bad for MP3 players D. hurts our ears If we listen to our MP3 player a
t a play, _________.
| A．the theatre won’t allow it | B．the actors will get angry |
| C．others won’t hear the play well | D．we will miss part of the play |
We can take one earphone out when we _________.
| A．show others the way | B．talk to friends on the phone |
| C．watch a sporting event | D．have dinner with our parents |
There are various ways in which individual economic units can interact with one another. Three basic ways may be described as the market system, the administered system, and the traditional system.
In a market system individual economic units are free to interact among each other in the marketplace. It is possible to buy commodities from other economic units or sell commodities to them. In a market, transactions may take place via barter or money exchange. In a barter economy, real goods such as automobiles, shoes, and pizzas are traded against each other. Obviously, finding somebody who wants to trade my old car in exchange for a sailboat may not always be an easy task. Hence, the introduction of money as a medium of exchange eases transactions considerably. In the modern market economy, goods and services are bought or sold for money.
An alternative to the market system is administrative control by some agency over all transactions. This agency will issue commands as to how much of each good and service should be produced, exchanged, and consumed by each economic unit. Central planning may be one way of administering such an economy. The central plan, drawn up by the government, shows the amounts of each commodity produced by the various firms and allocated to different households for consumption. This is an example of complete planning of production, consumption, and exchange for the whole economy.
In a traditional society, production and consumption patterns are governed by tradition; every person’s place within the economic system is fixed by parentage, religion, and custom. Transactions take place on the basis of tradition, too. People belonging to a certain group or caste（阶级） may have an obligation to care for other persons, provide them with food and shelter, care for their health, and provide for their education. Clearly, in a system where every decision is made on the basis of tradition alone, progress may be difficult to achieve. An inactive society may result.What is the main purpose of the passage?
| A．To outline contrasting types of economic systems. |
| B．To explain the science of economics. |
| C．To argue for the superiority of one economic system. |
| D．To compare barter and money-exchange markets. |
In the second paragraph, the underlined word “real” could best be replaced by _______.
| A．valuable | B．concrete | C．absolute | D．reliable |
According to the passage, a barter economy can generate ______.
| A．rapid speed of transactions | B．misunderstandings |
| C．inflation | D．difficulties for the traders |
According to the passage, who has the greatest degree of control in the administered system?
| A．Individual households. | B．Small businesses. |
| C．Major corporations. | D．The government. |
Which of the following is not mentioned by the author as a criterion（标准）for determining a person’s position in a traditional society?
| A．Family background | B．Age |
| C．Religious beliefs. | D．Custom |
The government-run command post in Tunis is staffed around the clock by military personnel, meteorologists and civilians. On the wall are maps, crisscrossed with brightly colors arrows that painstakingly track the fearsome path of the enemy.
What kind of invader gives rise to such high-level monitoring? Not man, not beast, but the lowly desert locust(蝗虫). In recent months, billions of the 3-inch-long winged warriors have descended on Algeria, Libya, Morocco and Tunisia, blackening the sky and eating up crops and vegetation. The insect invasion, the worst in 30 years, is already creating great destruction in the Middle East and is now treating southern Europe. The current crisis began in late 1985 near the Red Sea. Unusually rainy weather moistened the sands of the Sudan, making them ideal seedbed for the locust, which lays its eggs in the earth. The insect onslaught threatens to create yet another African famine. Each locust can eat its weight (not quite a tenth of an ounce) in vegetation every 24 hours. A good-size swarm of 50 billion insects eats up 100,000 tons of grass, trees and crops in a single night.
All ﹩150 million may be needed this year. The U.S. has provided two spraying planes and about 50,000 gal. of pesticide. The European Community has donated ﹩3.8 million in aid and the Soviet Union, Canada, Japan and China have provided chemical-spraying aircraft to help wipe out the pests. But relief efforts are hampered by the relative mildness of approved pesticides, which quickly lose their deadly punch and require frequent replications. The most effective locust killer dieldrin has been linked to cancer and is banned by many Western countries and some of the affected African nations. More than 5 million acres have been dusted with locust-killing chemicals; another 5 million will be treated by the end of June.
On May 30, representatives of Tunisia, Algeria, Libya, Morocco and Mauritania will meet in Algiers to discuss tactics to wipe out the ravenous swarms. The move is an important step, but whatever plan is devised, the locust plague promised to get worse before the insects can be brought under control.The main idea of the first sentence in the passage is that ______.
| A．the command post is stationed with people all the time. |
| B．the command post is crowded with people all the time. |
| C．there are clocks around the command post. |
| D．the clock in the command post is taken care of by the staff. |
The favorable breeding ground for the locust is ______.
| A．rich soil. | B．wet land |
| C．paces covered crops and vegetation | D．the Red Sea |
People are alert at the threat of the locust because ______.
| A．the insects are likely to create another African famine. |
| B．the insects may blacken the sky. |
| C．the number of the insects increases drastically. |
| D．the insects are gathering and moving in great speed. |
Which of the following is true?
| A．Once the pesticides are used, locust will die immediately. |
| B．Relief efforts are proved most fruitful due to the effectiveness of certain pesticides. |
| C．Dieldrin, the most effective locust killer, has been widely accepted in many countries. |
| D．Over 10 million acres of affected area will have been treated with locust-killing chemicals by the end of June. |
The purpose for affected nations to meet in Algiers on May 30 is ______.
| A．to devise anti-locust plans. |
| B．to wipe out the swarms in two years. |
| C．to call out for additional financial aid from other nations. |
| D．to bring the insects under control before the plague gets worse. |
It is pretty much a one-way street. While it may be common for university researchers to try their luck in the commercial world, there is very little traffic in the opposite direction. Pay has always been the biggest deterrent, as people with families often feel they cannot afford the drop in salary when moving to a university job. For some industrial scientists, however, the attractions of academia (学术界) outweigh any financial considerations.
Helen Lee took a 70% cut in salary when she moved from a senior post in Abbott Laboratories to a medical department at the University of Cambridge. Her main reason for returning to academia mid-career was to take advantage of the greater freedom to choose research questions. Some areas of inquiry have few prospects of a commercial return, and Lee’s is one of them.
The impact of a salary cut is probably less severe for a scientist in the early stages of a career. Guy Grant, now a research associate at the Unilever Centre for Molecular Informatics at the University of Cambridge, spent two years working for a pharmaceutical (制药的) company before returning to university as a post-doctoral researcher. He took a 30% salary cut but felt it worthwhile for the greater intellectual opportunities.
Higher up the ladder, where a pay cut is usually more significant, the demand for scientists with a wealth of experience in industry is forcing universities to make the transition (转换) to academia more attractive, according to Lee. Industrial scientists tend to receive training that academics do not, such as how to build a multidisciplinary team, manage budgets and negotiate contracts. They are also well placed to bring something extra to the teaching side of an academic role that will help students get a job when they graduate, says Lee, perhaps experience in manufacturing practice or product development. “Only a small number of undergraduates will continue in an academic career. So someone leaving university who already has the skills needed to work in an industrial lab has far more potential in the job market than someone who has spent all their time on a narrow research project.”By “a one-way street” in Paragraph One, the author means ________.
| A．university researchers know little about the commercial world |
| B．there is little exchange between industry and academia |
| C．few industrial scientists would quit to work in a university |
| D．few university professors are willing to do industrial research |
The underlined word “deterrent” most probably refers to something that ________.
| A．keeps someone from taking action | B．helps to move the traffic |
| C．attracts people’s attention | D．brings someone a financial burden |
What was Helen Lee’s major consideration when she changed her job in the middle of her career?
| A．Flexible work hours. |
| B．Her research interests. |
| C．Her preference for the lifestyle on campus. |
| D．Prospects of academic accomplishments. |
Guy Grant chose to work as a researcher at Cambridge in order to ________.
| A．do financially more rewarding work |
| B．raise his status in the academic world |
| C．enrich his experience in medical research |
| D．exploit better intellectual opportunities |
What contribution can industrial scientists make when they come to teach in a university?
| A．Increase its graduates’ competitiveness in the job market. |
| B．Develop its students’ potential in research. |
| C．Help it to obtain financial support from industry. |
| D．Gear its research towards practical applications. |
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