Question

Searching for life on other planets

For more than thirty 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 in outer space may be trying to get in touch with us. Scientists also have sent radio and television messages, as well as messages on spaceships traveling through space, on the chance that someone may receive 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 million channels at a time. Scientists are looking for any signal that stands out from the background noise.

Of the 200 billion stars in the Milky Way galaxy, scientists 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 life. Based on the planets in our galaxy, most scientists agree that one or more of these planets may support some life.

However, many scientists wonder whether intelligent life exists on other planets. Some believe that thirty years of searching without any intelligible messages shows that no one is out there. They say that 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 only about five billion years old, our galaxy 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.

To look for signals from distant stars, scientists _____.

A. have sent up spaceships to other planets

B. have sent radio and television messages to outer space

C. are listening to the radio messages all the year round

D. will use computers to pick up background noise

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.

Some scientists believe no other planet has life because ______.

   A. most of the researches have been done over the radio

   B. thirty years of searching doesn’t have any result

   C. we didn’t send messages on spaceships

   D. none of the other stars is right for life

Some scientists think there might be more advanced civilizations on other planets because _____.

A. some planets support more advanced civilizations

B. some civilizations have sent us signals we can’t recognize

C. the evolution of intelligence on other planets is unlike ours

D. some planets in our galaxy are much older than the earth

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. More advanced civilization than ours have developed on other planets.

Answer 1

【小题1】B

【小题2】A

【小题3】C

【小题4】D

【小题5】C

解析:

略