2. 外语
  3. Is there a population problem? My answer【C1】______the question is "YES", there is a problem. The scale of human activities is no

Is there a population problem? My answer【C1】______the question is "YES", there is a problem. The scale of human activities is no

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问题     Is there a population problem? My answer【C1】______the question is "YES", there is a problem. The scale of human activities is now so【C2】______that we are appreciably【C3】______the climate and ecosystems in our country, the U.S. and the world.
    The total【C4】______of people on the environment is【C5】______to each of two factors:
    A) The number of people, and
    B) The【C6】______impact of each person.
    If we are to【C7】______the total impact of people on the global environment, we must address the first, or preferably both, of these【C8】______
    There are many strong forces that will cause【C9】______growth of the average impact of each person on the global environment. To the extent that people in【C10】______countries【C11】______increase their material standard of living to levels more like ours, material consumption per capita will grow. So we are left with the imperative of【C12】______population growth, and then of studying the question, "Can this【C13】______population be sustained?’
    To gain a better appreciation of the seriousness of the problem, let us review some very elementary【C14】______Let us consider a【C15】______that is experiencing steady growth【C16】______such as 5% per year.
    First we note that this growing quantity will double【C17】______in a fixed time. This doubling time is found by【C18】______70 by the percent growth per year. For example, the doubling time for a steady growth rate of 5% per year is 70/5=14 years.
    Second, we note that a few doublings can give enormous numbers. It is convenient to remem-ber【C19】______ten doublings causes the growing quantity to increase in size by a factor of approximately 1000; twenty【C20】______will cause an increase by a factor of 1,000,000, etc.
【C16】
选项 A、on a rate
B、at a rate
C、of a rate
D、at rate
答案B
解析 语义衔接题。与rate搭配的介词通常是at，故可以在at a rate和at rate之间选择，rate前通常需要加不定冠词，故答案为B。
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