Question

In the atmosphere, carbon dioxide acts rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun's rays to enter but prevents the heat from escaping.

　　 According to a weather expert' s prediction, the atmosphere will be 3℃ warmer in the year 2050 than it is today, if man continues to burn fuels at the present rate. If this warming up took place, the ice caps in the poles would begin to melt, thus raising sea level several metres and severely flooding coastal cities. Also, the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere (北半球), possibly resulting in an alteration of the earth's chief food growing zones.

　　  In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming, in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.

　　  Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth.

　　  However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude , therefore, that up to now natural influences on the weather have gone beyond those caused by man. The question is: Which natural cause has most effect on the weather?

　　  One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and "cold" spots (that is, the relatively less hot spots) on the sun. As the sun rotates (使旋轉(zhuǎn)), every 27. 5 days, it presents hotter or "colder" faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth's atmospheric pressure, and consequently on wind circulation. The sun is also changeable over a long term: its heat output goes up and down in cycles, the latest trend being downward.

　　  Scientists are now finding shared relations between models of solar weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia (慣性) of the earth's climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful opposed balance to the sun's fading heat .

66. It can be concluded that a concentration of carbon dioxide in the atmosphere would_________.

   A. mean a warming-up in the Antarctic

   B. raise the temperature of the earth' s surface

C. prevent the sun's rays from reaching the earth's surface

D. explain the cause of  great changes in the climate in the northern hemisphere

67.The article was written to explain ___________. 

A. the greenhouse effect

B. the solar effects on the earth

C. the causes affecting weather

D. the models of solar-weather interactions

68. Although the fuel consumption is greater in the northern hemisphere, temperatures there　seem to be falling. This is__________.

 A. mainly because the levels of carbon dioxide are rising

 B. partly due to changes in the output of solar energy

C. possibly because the ice caps in the poles are melting

D. only due to the effect of the inertia of the earth' s climate

69. On the basis of their models, scientists believe the opinion that__________.

A. the climate of the world should be becoming cooler

B. the new Ice Age will be delayed by the greenhouse effect

C. the man-made warming effect helps to increase the solar effects

D. it will take thousands of years for the inertia of the earth's climate to take effect

70. If the assumption about the delay of a new Ice age is correct, ____________.

A. ice would soon cover the northern hemisphere

B. the greenhouse effect could work in favor of the earth

C. the best way to overcome the cooling effect would be to burn more fuels

D. the increased levels of carbon dioxide in the atmosphere could warm up the earth even more quickly

Answer 1

66---70  BCBAB

解析:

文章大意：這是一篇科普文，分析全球變暖的真正原因，到底是因為人類生活排放的二氧化碳還是因為太陽活動，今天的天氣狀況并沒有印證若干年前的科學(xué)預(yù)測。

66.B細(xì)節(jié)理解題。由文章第一段可知大量二氧化碳集中在一起，會使地球表面的溫度升高。因為二氧化碳的作用就象單向的鏡子或者溫室的玻璃屋頂一樣只允許陽光進(jìn)來，而里面的熱卻無法散去。

67．C主旨大意題。文章第一至第四段解釋二氧化碳對全球氣候的影響，而第五、六段又懷疑二氧化碳的作用，分析太陽活動對全球變暖的影響。由此看來，文章的目的是解釋影響天氣的原因。

68．B細(xì)節(jié)理解題。文章第五段提出北半球消耗燃料多，排放的二氧化碳量大，按道理北半球氣候應(yīng)升高但實際反而下降，什么原因？第六段從太陽活動解釋了上述疑問：可能部分是由于太陽能量釋放的不同。

69．A細(xì)節(jié)理解題。由最后一段第二句”The problem is that the models are predicting that the world should be entering a new Ice Age and it is not”可以推測科學(xué)家認(rèn)為地球氣候應(yīng)變冷，而入新的冰河時期。

70．B推理判斷題。如果新的冰河時期推遲的假設(shè)正確，可能是因為地球表層的二氧化碳起的保溫作用。