2016年12月英语四级模拟试题及答案

　　56. Apart from this new understanding of the correlation between health and exercise, the main reason the passage gives for why so many Americans are exercising regularly is ________.

　　[A] their changed life style

　　[B] their eagerness to stay thin and youthful

　　[C] their appreciation of the importance of exercise

　　[D] the encouragement they have received from their companies

　　Passage Two

　　Questions 57 to 61 are based on the following passage.

　　We can begin our discussion of "population as global issue" with what most persons mean when they discuss "the population problem": too many people on earth and a too rapid increase in the number added each year. The facts are not in dispute; it was quite right to employ the analogy that likened demographic growth to "a long, thin powder fuse that burns steadily and haltingly until it finally reaches the charge and explodes".

　　To understand the current situation, which is characterized by rapid increases in population, it is necessary to understand the history of population trends. Rapid growth is a comparatively recent phenomenon. Looking back at the 8,000 years of demographic history, we find that populations have been virtually stable or growing very slightly for most of human history. For most of our ancestors, life was hard, often nasty, and very short. There was high fertility in most places, but this was usually balanced by high mortality. For most of human history, it was seldom the case that one in ten persons would live past forty, while infancy and childhood were especially risky periods. Often, societies were in clear danger of extinction because death rates could exceed their birthrates. Thus, the population problem throughout most of history was how to prevent extinction of the human race.

　　This pattern is important to notice. Not only does it put the current problems of demographic growth into a historical perspective, but it suggests that the cause of rapid increase in population in recent years is not a sudden enthusiasm for more children, but an improvement in the conditions that traditionally have caused high mortality.

　　Demographic history can be divided into two major periods: a time of long, slow growth which extended from about 8000 B.C. till approximately 1650 A.D. In the first period of some 9,600 years, the population increased from some 8million to 500 million in 1650. Between 1650 and 1975, the population has increased from 500 million to more than 4 billion. And the population reached 6.2 billion throughout the world by the year 2000. One way to appreciate this dramatic difference in such abstract numbers is to reduce the time frame to something that is more manageable. Between 8000 B.C. and 1650, an average of only 50,000 persons was being added annually to the world's population. At present, this number is added every six hours. The increase is about 80,000,000 persons annually.

　　57. The word "demographic" (Line 4, Para. 1) means ________.

　　[A] statistics of human

　　[B] surroundings study

　　[C] accumulation of human

　　[D] development of human

　　58. Which of the following demographic growth patterns is most suitable for the long thin powder fuse analogy?

　　[A] A virtually stable or slightly decreasing period and then a sudden explosion of population.

　　[B] A slow growth for a long time and then a period of rapid, dramatic increase.

　　[C] Too many people on earth and a few rapid increase in the number added each year.

　　[D] A long period when death rates exceed birthrates and then a short period with higher

　　fertility and lower mortality.

　　59. During the first period of demographic history, societies were often in danger of extinction

　　because ________.

　　[A] only one in ten persons could live past 40

　　[B] there was higher mortality than fertility in most places

　　[C] it was too dangerous to have babies due to the poor conditions

　　[D] our ancestors had little enthusiasm for more children