In the 20th century the planet's population doubled twice. It will not double even once in the【C1】______century, because birth rates in much of the world have【C2】______steeply. But the number of people over 65 is set to【C3】______within just 25 years. This shift in the structure of the population is not as momentous as the【C4】______that came before. But it is more than enough to reshape the world economy. 【C5】______the UN's population【C6】______, the standard source for demographic estimates, there are a-round 600m people aged 65 or older【C7】______today. That is in itself remarkable; the author Fred Pearce claims it is【C8】______that half of all the humans who have ever been over 65 are alive today. But【C9】______a share of the total population, at 8%, it is not that【C10】______to what it was a few decades ago. By 2035,【C11】______, more than 1. 1 billion people—13% of the population—will be above the age of 65. This is a【C12】______result of the dropping birth rates that are slowing overall population growth; they mean there are【C13】______fewer young people around. The "old-age dependency ratio"—the ratio of old people to those of working age—will【C14】______even faster. In 2010 the world had 16 people aged 65 and over for every 100 adults between the ages of 25 and 64,【C15】______the same ratio it had in 1980. By 2035 the UN【C16】______that number to have risen to 26. In rich countries it will be much higher. Japan will have 69 old people for every 100 of working age by 2035, Germany 66.【C17】______America, which has a relatively high【C18】______rate, will see its old-age dependency rate rise by more than 70% , to 44. Developing countries,【C19】______today's ratio is much lower, will not see absolute levels rise that high;【C20】______the proportional growth will be higher. Over the same time period the old-age dependency rate in China will more than double from 15 to 36. Latin America will see a shift from 14 to 27.
单选题
【C1】
【正确答案】
C
【答案解析】解析：形容词辨析题。根据该句的will这个时态，可知该句要描述的事情发生在将来，故[A]previous先前的，可以排除；而[B]prosperous繁荣的和[D]chronic长期的与前面的20th century无法互相照应。本文开篇第一句是说In the 20th century，第一句中doubled是过去时，说明20世纪是过去，而第二句中的will指示了未来，并且联系现实，我们现在正处于21世纪，符合作者写本文的时代背景。故答案为[C]current当前的。
【答案解析】解析：动词辨析题。[A]decrease减少；[B]double翻倍；[C]increase增加；[D]halve减半。根据第三空前面的But一词可以推断，该句表述的内容跟上文表述的内容相反，上文提到：本世纪世界人口数量不会翻倍；本句提到：但是老人数量在25年内会 3 。可以推断出该空的最佳答案为[B]，这样才能与上文的will not double形成对比转折。
【答案解析】解析：词义辨析题。[A]projects工程；[B]projections预测；[C]subjects主题；[D]objections反对。根据下文的the standard source for demographic estimates一句可以得出答案，该句是对前面信息的进一步解释，也就是跟前面的信息同义替换，其中demographic estimates “人口统计预测”=population projections“人口预测”。故答案为[B]。
单选题
【C7】
【正确答案】
D
【答案解析】解析：形容词辨析题。选项[A]vivid生动的可以先排除，我们一般不说人很生动。[C]survived幸存的也比较容易排除，因为一般指在事故中存活。答案在[B][D]之间。而living，alive两词的词性、意思都一样，都可以形容人，区别在于living一般作前置定语，如living man；alive作后置定语或表语，如man alive；故该句填入alive是正确的；且该词与下文的half of all the humans who have ever been over 65 are alive today中的alive形成“原词复现”，故答案为[D]。
【答案解析】解析：副词辨析题。[A]mainly主要地；[B]consequently结果；[C]partly部分地；[D]proportionally成比例地，相称地。从下文的the ratio of old people to those of working age“老年人和工作年龄群体的比例”中ratio一词得到提示，该空填的是[D]proportionally。[A][C]两项均无法搭配；[B]consequently的位置则一般置于句首；故本题答案为[D]。
单选题
【C14】
【正确答案】
A
【答案解析】解析：词义辨析题。[A]grow增长；[B]drop下降；[C]remain保持；[D]decay衰退。根据该段最后一句“By 2035 the UN 16 that number to have risen to 26．”中的“risen”一词判断该空应该填入grow，故答案为[A]。
单选题
【C15】
【正确答案】
C
【答案解析】解析：副词辨析题。[A]actually实际上；[B]certainly肯定地；[C]almost几乎；[D]already已经。原文说2010年老年人的比例与1980年几乎一样，仅从搭配上来看，almost the same是最合适的，故[C]为答案。