The monitor wanted to buy two_______ stamps, but the salesgirl only sold him_______ these stamps.

A. scores of; dozens of　　   B. scores; dozen of　　

C. score of; dozen of　　     D. score of;  dozen

For more than twenty years scientists have been searching for signs of life on other planets. Most of these searches have been done over the radio. The hope is that someone on outer space may be trying to get in touch with us. Scientists also have sent radio and television messages on spaceships travelling through space, on the chance that someone may be receptive to such messages.

Scientists are using powerful radio telescopes to listen to signals from about 1,000 stars, all within 100 light years of earth. In addition, they will scan the entire sky to “listen” for radio messages from more distant stars. Using a computer, they will be able to monitor more than eight channels at one time. Scientists are looking for any signal that stands out from the background noise.

Of the 200 billion stars in the Milky Way galaxy(银河星系), scientist find that five percent are like our sun. Perhaps half of them have a planet like earth. Such a planet would be a reasonable distance from the star for temperatures to be right for the evolution of life. Based on the inhabitable (that can be lived in) planets in our galaxy, most scientists agree that chances are likely that one or more of these planets supports some life.

However, many scientists wonder whether intelligent life exists on other planets. Some believe that twenty years of searching without any intelligible message shows that no one is out there. They say that the evolution of intelligence comparable to ours is unlikely.

Other scientists believe that our search hasn’t been long enough to rule out the possibility that intelligent life exists in our galaxy. Although our sun family is about 20 billion years old. In that time, some scientists think it is likely that civilizations much more advanced than ours have developed. Perhaps these civilizations send us no signals; perhaps we have not recognized the signals they have sent us. If we hope to find intelligent life, these scientists believe that we have to keep looking.

1. According to the passage, how many planets in our galaxy might be inhabitable?

A. 5 billion.　　　　　　 B. 10 billion.

C. 15 billion.　　　　　　 D. 200 billion.

2. The first paragraph in this passage is mainly about 　　　　 .

A. how scientists are looking for signs of life on other planets

B. why scientists are looking for signs of life on other planets

C. where scientists are looking for signs of life on other planets

D. when scientists are looking for signs of life on other planets

3. The underlined word “monitor” in the second paragraph means “　　　　 ”.

A. find　 B. follow　 C. check　 D. form

4. Which of these statements is TRUE based on the information in the passage?

A. The earth is one of the oldest planets in our galaxy.

B. Most scientists believe that there is intelligent life on other planets.

C. Scientists are trying different ways to find signs of life on other planets.

D. Scientists don’t believe that there might be life on other planets.

 

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.

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

During an earthquake in China in 1975, _________.

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

Which of the following is one of earthquake nerves according to the passage?

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.

The scientists did an experiment with a group of dogs to _________.

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

Simply by analyzing a drop of blood, a doctor will be able to diagnose a birth defect or even cancer when it is in the early stage; using new technology, a material lighter but much stronger than steel can be produced.

These may sound like dreams at present. But the dreams may soon come true as research findings in laboratories are being turned into products more rapidly in the new century, according to experts participating in the fourth Asia-Pacific Economic Cooperation (APEC) Technomart, a technology exhibition and trade fair in Suzhou.　　

"Most people think nano-technology（纳米技术）is too far-fetched to be real. But in fact nano-technology has been applied in a wide range of fields, such as medicine. It is coming into our daily life," said Cheng Jiachong from a Hong Kong-based nano-technology firm.

Nano-technology based on the nanometer, the unit of which is a billionth of a meter, enables scientists to have new concepts of disease diagnosis and treatment on a molecular（分子）and atomic scale, Cheng said.　　

By using nanometer particles, a doctor can separate the fetus cells（胚胎细胞）from the blood of a pregnant woman to see if the development of the fetus is normal. This method is also being used in the early diagnosis of cancer and heart disease, he said.　　

One of the most significant impacts of nano-technology is at the bio-inorganic materials interface, according to Greg Tegart, executive advisor of the APEC Center for Technology Foresight.　　

"By combining enzymes（酶）and silicon chips we can produce biosensors. These could be implanted in humans or animals to monitor health and to deliver corrective doses（剂量）of drugs," he told the participants a technology forum during the exhibition.　　

"Nano-technology could affect the production of nearly every man-made object, from automobiles, tires and computer circuits（电路）, to advanced medicines and tissue replacement, and lead to the invention of objects yet to be imagined," said David Minns, a special advisor to the National Research Council of Canada.　　

It has been shown that carbon nano-tubes are ten times as strong as steel, with one sixth of the weight, and nano-scale systems have the potential to make supersonic transport cost- effective and to increase computer efficiency by millions of times, he said.

The experts agreed that the APEC technology exhibition and trade fair provided many chances for exchanges of innovative ideas and products.

1.Realization of the dreams mentioned in the first paragraph will mainly base on ________.

A. APEC                              B. Chinese scientist   

C. the APEC Center for Technology Foresight     D. Nano-technology

2.The length of a nanometer equals to ______.

    A.  meter         B.  meter      C.  meter        D.  meter

3. We can imply from what David Minns said that _________.

A. Nano-technology could only be used to invent new objects.

B. Nano-technology could be widely used to produce or invent objects.

C. Nano-technology is a money-consuming technology.

D. Nano-technology can not be used to improve the service of Internet.

4. Compared to steel, carbon nano-tubes are ________.

A. stronger and lighter      B. lighter but as strong

C. stronger but as light                                     D. poor in quality