题目内容
________ the earth to be flat, many feared that Columbus would fall of the edge of the earth．
- A.Having believed
- B.Believing
- C.Believed
- D.Being believed
解析：
“认为”是一个主动行为，因此，需要一个表示主动的分词，选项C和D被排除。A项强调分词所表示的主动动作早于后面的动作(常常表示时间，而此处是表示原因)，语法搭配不合适，所以答案是B项。句意为：许多人认为地球是扁的，因此害怕哥伦布会从地球的边缘掉下。
LONDON: What could possibly be wrong with planting trees? The benefits are obvious; they firm the soil, soak up (摄取) extra water and take carbon dioxide (二氧化碳) out of the atmosphere.
However, it now turns out that planting trees could add to global warming.
Tree roots do a great job of keeping soil firmly on the ground and out of the wind’s power. The problem is that some of those dust clouds play an important part in taking in carbon dioxide.
Huge dust storms blow out over the oceans from dry parts of North Africa and central Asia. Tons of dust are lifted and left as a thin film over the ocean surface. The dust fuels oceanic life.
Dust from China is carried east and left in the Pacific Ocean. If a tree-planting programme there is successful and the dust supply reduced, the final result may be that less carbon dioxide gets locked away in the ocean.
Andy Ridgwell, an environmental scientist from the University of East Anglia, has spent the past few years studying dust and says his work “shows clearly the complexity of the system and the importance of not tinkering(粗劣地修补) with it without understanding the results. For this reason the need is to focus(集中) on cutting carbon dioxide giving off rather than monkeying (瞎弄) about with the land surface.”
An American scientist, Robert Jackson, has shown that when native grassland areas are invaded(侵入) by trees, carbon is lost from the soil. “We are studying why the soil carbon disappears, but one theory is that trees do a lot more of their growing above ground compared to grasses, so less carbon goes directly into the soil from trees, ” says Jackson.
In wet areas of the world, the gain from trees absorbing carbon dioxide above ground seems to be outweighed(超过) by the loss of carbon from the soil below ground. Countries that plan to combat global warming by planting trees may have to think again.
Solutions to environmental problems are often more complex than they first appear, and understanding the Earth’s climate is a very great challenge.
【小题1】People usually hold the opinion that_____________.
| A．huge dust storms can destroy carbon dioxide |
| B．huge dust storms can destroy the oceans on the earth |
| C．huge dust storms can’t do anything beneficial for man |
| D．planting trees is the only way to control huge dust storms |
| A．dust plays a more important part than trees |
| B．trees shouldn’t have been planted in dry places |
| C．carbon dioxide is harmful to everything on the earth |
| D．environmental problems are more complex than expected |
| A．grassland areas should be covered by forests |
| B．trees hold more carbon than grasses |
| C．carbon can turn grass into dust |
| D．less carbon can make trees grow faster |
Most earthquakes occur within the upper 15 miles of the earth’s surface, but earthquakes can and do occur at all depths to about 460 miles. Their number decreases as the depth increases. At about 460 miles one earthquake occurs only every few years. Near the surface earthquakes may run as high as 100 in a month, but the yearly average does not vary much.
The extent of the disaster in an earthquake depends on many factors. If you carefully build a toy house with an erect set (坚立架), it will still stand no matter how much you shake the table. But if you build a toy house with a pack of cards, a slight shake of the table will make it fall. An earthquake in Agadir was not strong, but it completely destroyed the city. Many stronger earthquakes have done comparatively little damage. If a building is well constructed and built on solid ground, it will resist an earthquake. Most deaths in earthquakes have been due to faulty building construction or poor building sites. A third and very serious factor is panic. When people rush out into narrow streets, more deaths will result.
There is one type of earthquake disaster that little can be done about. This is the disaster caused by seismic (地震的) sea waves, or tsunamis (海啸). These are often called tidal waves, but the name is incorrect. They had nothing to do with tides. In certain areas, earthquakes take place beneath the sea. These submarine earthquakes sometimes give rise to seismic sea waves. The waves are not noticeable out at sea because of their long wave length. But when they roll into harbors, they pile up into walls of water 6 to 60 feet high. The Japanese call them “tsunamis” meaning “harbor waves”, because they reach a sizable (相当大的) height only in harbors.
Tsunamis travel fairly slowly, at speeds up to 500 miles an hour. An earthquake warning system is in use to warn all shores likely to be reached by the waves. But this only enables people to leave the threatened shores for higher ground: There is no way to stop the oncoming wave.
【小题1】Which of the following can NOT be concluded from the passage?
| A．The number of earthquakes is closely related to the depth. |
| B．Roughly the same number of earthquakes occur each year. |
| C．Earthquakes are impossible at depths over 460 miles. |
| D．Earthquakes are most likely to occur near the surface. |
| A．faulty building construction |
| B．an earthquake’s strength |
| C．widespread panic in earthquakes |
| D．ineffective instruments |
| A．their high speed |
| B．the wide shores |
| C．their silent movements |
| D．their long wave length |
| A．help reduce fear |
| B．find ways to stop them |
| C．be warned early enough |
| D．develop warning systems |
| A．two | B．five | C．four | D．three |
Will life in the future be better, worse or the same as now? Futurologists（未来学家）predict that life will probably be very different in 2050.
First of all, it seems that TV channels will have disappeared by 2050. A computer will send the program directly to the television. On TV screen appear holograms（全息图）, which are pictures with certain height, width and depth. We will be able to see, smell and touch the things that we see on television.
Water has become one of our most serious problems. Agriculture is changing and people are growing more fruit and vegetables to export. Demand for water will increase ten times in 2050. Some futurologists predict that water will be the cause of war if we don’t act now.
In transport, cars will run on new fuels and go very fast. A car will have computers to control its speed and there won’t be any accidents. On the other hand, space planes will take people around the earth in about three hours. People will fly from Los Angeles to Tokyo by space plane in just half an hour.
In the field of technology, robots will have replaced people in factories. By 2050, we will see robots everywhere. They do not ask for pay rises or go on strike, and they work 24 hours a day.
Medicine technology will have conquered many diseases by 2050; we will be able to help blind and deaf people see again and hear again. Scientists have discovered how to control genes. They have already produced clones of animals and will be able to produce clones of people and decide how they look, how they behave and how much intelligence they have. If you want all this to come true, you should study science and technology hard.
【小题1】What is the main difference between today’s and 2050’s TV?
| A．We can use a computer to turn off the TV set. |
| B．We can talk with the characters appearing on TV. |
| C．We can choose whatever we like to see on TV. |
| D．We can touch the things we see on TV. |
| A．Technology. | B．Medicine. | C．Movies. | D．Agriculture. |
| A．The lack of water. | B．The less farmland. |
| C．The shortage of robots. | D．The more space planes. |
| A．people will spend less time in studying |
| B．more and more people needn’t go to school |
| C．people will have more time to relax or rest |
| D．no patients will be found in the world |
Scientists who try to predict earthquakes have gotten some new helpers recently—animals.
That’s right, animals. Scientists have begun to understand what farmers have known for thousands of years. Animals often seem to know in advance that an earthquake is coming, and they show their fear by acting in strange ways. Before a Chinese quake in 1975, snakes awoke from their winter sleep early only to freeze to death in the cold air. Cows broke their halters (缰绳) and tried to escape. Chickens refused to enter their cage. All of this unusual behavior, as well as physical changes in the earth, warned Chinese scientists of the coming quake. They moved people away from the danger zone and saved thousands of lives.
One task for scientists today is to learn exactly which types of animal behavior predict quakes. It’s not an easy job. First of all not every animal reacts to the danger of an earthquake. Just before a California quake in 1977, for example, an Arabian horse became very nervous and tried to break out of his enclosure. The Australian horse next to him, however, remained perfectly calm. It’s also difficult at times to tell the difference between normal animal restlessness and “earthquake nerves”. A zoo keeper once called earthquake researchers to say that his cougar had been acting strangely. It turned out that the cat had an upset stomach.
A second task for scientists is to find out exactly what kind of warnings the animals receive. They know that animals sense far more of the world than humans do. Many animals can see, hear, and smell things that people do not even notice. Some can sense tiny changes in air pressure, gravity, or the magnetism of Earth. This extra sense probably helps animals predict quakes.
A good example of this occurred with a group of dogs. They were shut in an area that was being shaken by a series of tiny earthquakes. (Several small quakes often come before or after a large one.) Before each quake a low booming sound was heard. Each boom caused the dogs to bark wildly. Then the dogs began to bark during a silent period. A scientist who was recording quakes looked at his machine. It was acting as though there were a loud noise too. The scientist realized that the dogs had reacted to a booming noise. They also sensed the tiny quake that followed it. The machine recorded both, though humans felt and heard nothing.
In this case there was a machine to monitor what the dogs were sensing. Many times, however, our machines record nothing extraordinary, even though animals know a quake is coming. The animals might be sensing something we measure but do not recognize as a warning. Discovering what animals sense, and learning how they know it is a danger signal, is a job for future scientists.
【小题1】Through the passage the writer hopes to explore __________.
| A．why animals send a danger signal before an earthquake |
| B．how animals know when an earthquake is coming |
| C．why animals not men have good sense of danger |
| D．how much animals know about an earthquake |
| A．chickens refused to go out of their cage |
| B．snakes were frozen to death in their caves |
| C．snakes awoke from their winter sleep earlier |
| D．cows broke their halters and escaped from their sheds |
| A．An Arabian horse tried to escape from his enclosure. |
| B．A cougar had an upset stomach unexpectedly. |
| C．An Australian horse was perfectly calm. |
| D．A cat acted very strangely in a zoo. |
| A．find out that the machine could record unusual happenings |
| B．compare the reactions of animals and those of humans |
| C．prove that animals could sense more than humans |
| D．find out what exact warnings animals sent |