2007年6月23日大学英语六级考试真题预测及参考答案

   
31. A medical explanation as to the question why women live longer than men is that          .
A) women have to live long enough to look after grandchildren
B) women’s hearts hardly grow old
C) women have more endurance than men
D) women are superior at evolutionary scale
32. The power of the female heart remains undiminished between the ages of 18 and 70 probably because          .
A) women almost lose no contractile muscle cells in the walls of their hearts
B) women’s oestrogen has a protective effect on their heart
C) the size of their heart chambers is different from men’s
D) the thickness of the female heart’s muscular wall is different from men’s
33. Dr. Goldspink disagrees with the proposal that oestrogen could protect heart because          .
A) female sex hormone can increase blood flow
B) female sex hormone can be beneficial to blood vessels
C) female heart function hardly drops when oestrogen levels fall greatly
D) female heart function improves though not obviously
34. What Dr. Goldspink says to men is that          .
A) men can’t recover lost heart function in any way
B) men can recover lost heart function at any age
C) proper exercise does good to the heart at any age
D) it’s too late to start exercise when men are getting old
35. The best title of the passage is          .
A) Exercise and the Health of Heart
B) The Difference between Men and Women
C) Heart and Health
D) Why Do Women Live Longer than Men
Passage Four
Questions 36 to 40 are based on the following passage.
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 warm 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 exceeded 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 rotated, 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 variable over a long term: its heat output goes up and down in cycles, the latest trend being downward.
Scientists are now finding mutual 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 of the earth’s climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful counter-balance to the sun’s diminishing heat.
36. Experts used to believe that the chief reason for global warming is          .
A) that most fuel is consumed in the northern hemisphere
B) human activities
C) natural influences and carbon dioxide
D) the solar energy