.
The journey to the moon had been the first step toward future exploration(探险) in space. The distance between the Moon and Earth is very short indeed when compared with the distances between Earth and the other planets. Mars, the nearest planet to Earth is millions of miles away. Traveling to the planets will be man’s next aim. Such travels will be more challenging than the trip to the moon and certainly more adventurous.
Recently, two American spaceships, Vikings 1 and 2, landed on Mars trying to discover whether that planet has any life on it. So far the signs of life on Mars has neither confirmed(确认) nor ruled out. Russians have discovered that the surface of Venus(金星) is so hot that it is almost certain that there is no life there. Also the atmosphere of Venus is extremely dense(稠) and the pressure is nearly a hundred times greater than that of the Earth’s atmosphere.
Scientists believe man may find planets which have the same conditions as those we have on Earth , but man should realize Earth will be his only home for a long time and begin to love and care for it.
63. According to the passage, traveling to the planets will be ________.
A. much easier and even more interesting B. far more exciting and dangerous
C. man’s final aim D. man’s first step
64. Which of the following is Not true?
A. Mars is nearer to the earth than the moon.
B. The moon is much nearer to the earth than Mars.
C. Of all the planets, Mars is the nearest to the earth.
D. All the planets are much farther to the earth.
65. From the passage, we can guess_____.
A. there is life on Mars
B. there is no life on Mars
C. the atmosphere of Mars is not so dense as that of Venus
D. scientists will have little hope to find the answers
66. Man can live on under the conditions of _______.
A. much too hot surface B. the same pressure as we get on earth
C. normal atmosphere as we have on earth D. both B and C
.
Damage to Ozone layer Gets Worse
In the middle of winter, when snow is falling in many parts of the United States, scientists have sounded a warning to people who plan to spend many hours in the sun this summer. The warning is: The sun’s summertime rays are more dangerous than once thought.
A team of scientists from 80 nations recently reported to the United Nations that a layer of ozone (臭氧层) in the atmosphere, which protects humans from harmful levels of ultraviolet radiation（紫外线辐射）, will be thinner over the United States this summer. The thinner layer allows more ultraviolet rays from the sun to reach Earth. The extra amount of ultraviolet radiation could cause an increase in the number of cases of skin cancer.
Scientists first became concerned about the ozone layer in the mid-1980s when a hole was discovered in the layer above Antarctica during the winter. The hole was caused by chemicals used in refrigerators and air conditioners. When these chemicals are sent out into the atmosphere, they produce gases that destroy the ozone.
Concern about the protective ozone layer rose more recently when data(数据) from satellites and ground stations showed that ozone levels were dropping over areas other than Antarctica. Low ozone levels were recorded in the spring and summer over the United States and over other populated areas in the world.
Although many countries have already begun stopping the use of ozone destroying chemicals, the new findings are expected to advance the timetable for a total ban(禁止) of the chemicals.
59. The scientists have observed the ozone layer_____.
A. since 1980 B. since last winter
C. for about 20 years D. for about one year
60. The ozone layer in the atmosphere can _____.
A. do a lot of good to human beings in many ways.
B. protect humans from diseases caused by bad weather.
C. do a lot of harm to human beings in the summer-time.
D. protect humans from harmful levels of ultraviolet radiation.
61. Scientists first found that there was a hole in the ozone layer_____.
A. above Arctic during the winter in the mid-1980s
B. above Antarctica during the winter in the mid-1980s
C. over somewhere in the north of the equator in 1980
D. over the U.S.A in the summertime in the mid-1980s
62. The damage to the ozone layer was caused by_____.
A. the changeable weather
B. ozone-destroying chemicals
C. chemicals from refrigerators
D. chemicals from air conditioners
.
_________ it was to become was a mystery until the dust began to slowly combine into a ball moving around the sun.
|
A．That |
B．What |
C．Which |
D．Whether |
.
I'm amazed that Mr Harris _________ have said nothing about the matter.
|
A．can |
B．should |
C．would |
D．must |
.
— I will take my mid-term exam tomorrow.
—_________.
|
A．Forget it |
B．Congratulations |
C．That’s all right |
D．Good luck |
.
Look at the sign, Sir. We don’t permit _________ in the hall.
|
A．smoke |
B．to smoke |
C．smoking |
D．to have a smoke |
