据人口学家统计和预测，墨西哥等发展中国家的人口翻一番需20～40年，美国需40～80年，瑞典人口将会相对稳定，德国人口将减少。专家们对人口增减动态的预测依据是
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A．种群数量和密度B．种群年龄结构C．种群性别比例D．出生率和死亡率
相关热点： 人口学家 出生率 死亡率
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B:李雪芮的协调性和爆发力十分突出，在众多体校的孩子中出类拔萃，是一个不可多得的网球运动方面的天才。
C:人口学家及经济学家们认为，放宽生育政策后，新生人口的增加在当下对刺激消费、增加就业岗位不无裨益。
D:凭借《三体》获第73届世界科幻大会颁布的雨果奖的刘慈欣，被授予特级华语星云勋章和2015年度中央电视台科技创新人物。
In “Relax, We’ll Be Fine”, columnist David Brooks writes, “the fact is, despite all the problems, America’s future is extremly bright.”
Mr. Brooks acknowledges that “According to recent survey, 60 percent of Americans think the country is heading in the wrong direction. The same percentage believe that the U.S. is in long-term decline. The political system is not functional. A financial crisis looks unavoidable. There are plenty of reasons to be sad.”
But, he writes:
“Demographers（人口学家) predict that over the next 40 years, the U.S. population will increase by an additional 100 million people, to 400 million over all. The population will be determined, hardworking and relatively young. In 2050, only a quarter will be over 60, compared with 31 percent in China and 41 percent in Japan.”
As the rising generation leads an economic recovery, it will also participate in a communal
（of community) one. We are living in a global age of social entrepreneurship（创业精神).
In sum, the U.S. is on the edge of a demographic, economic and social recovery, built on its historic strengths. The U.S. has always been good at destructive change. And it’s always been good at decentralized community-building, too. Surely a country with this much going for it is not going to wait around passively and let a rotten political culture drag it down.
51．In his article Relax, We’ll Be Fine, David Brooks intends to________.
A．encourage Americans to be optimistic about their future
B．give Americans courage to face their financial crisis
C．persuade Americans to live happily and generously
D．inspire Americans to lead an economic recovery
52．There are all the reasons for Americans to be unhappy except____
A．the function-failed political system B．the increasing population
C．the declining economy D．the wrong direction and financial crisis
53．Over the next 40 years, according to David Brooks, Americans will be____
A．more optimistic and humorous B．more pessimistic and stronger
C．more energetic and promising D．more considerate and aggressive
54．In the author’s opinion, America________.
A．has always benefited from wars B．has done well by its political system
C．has contributed a lot to human progress D．has contributed to world’s economy
55．We can learn from the passage that____
A．American political system and culture are backward
B．Americans are not a nation to give in to difficulties
C．Americans are very destructive and aggressive
D．America has been in an economic and social recovery
地质学家在完成对M洲的矿产勘察工作后惊叹：“这是世界上最富饶的大洲。”社会学家在调查完M洲人民的生活水平后叹息：“这是世界上最贫穷的大洲。”人口学家在测算了M洲的人口状况后感叹：“M洲将成为世界上最大的大洲。，回答1～2题：
1．M洲指的是
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A．亚洲B．拉丁美洲C．欧洲D．非洲
2．“M洲将成为世界上最大的大洲”中的“最大的大洲”的涵义是
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A．人口最多B．面积最大C．经济最发达D．发展最快
B:钓鱼岛争端，是日本不但政治陷入混乱，更是冲击日本脆弱的经济形势，之前日本公然叫嚣
C:动画片《孔子》用动漫形式塑造的全新的孔子形象，打破了以往人们对国学刻板而僵化的思维习惯，受到社会各界的广泛关注，并多次获得国家奖项。
D:人口学家及经济学家认为，放宽生育政策后新生人口的增加在当下对刺激消费、增加就业岗位不无裨益。
中国的邻邦日本，正在遭受“人口少子化”的困扰。1989年，日本的总和生育率下降到1．57，被称为“1．57”危机。2005年，这一数字下挫到1．08，日本媒体惊呼“少子化已达危害国家兴衰地步”。与此同时。在人口众多的中国，少子化问题也日渐浮现。根据2010年第六次全国人口普查的统计数据，我国0到14岁人口占人口总数的16．60％，比2000年下降了6．29个百分点，总和生育率约为1．18。人口学家惊呼：中国已经步入超低生育率和严重少子化国家行列。这段文字意在强调()。
A．中国少子化的现象尚未引起国人的足够关注
B．少子化已经成为困扰我国经济发展的社会问题
C．中国少子化程度严重，总和生育率甚至低于日本
D．我们要重视人口少子化问题所带来的威胁