填空题. Now what began in Japan is happening globally. As David Brooks wrote in his New York Times column yesterday, fertility is on decline in 1 much of the world, from Iran—1.7 births per woman—to Russia, which 2 low fertility combines with high death rates means the population is 3 already shrinking. To Brooks, the world is facing with what the writer 4 Phillip Longman has called the gray tsunami—a moment the population over 60 swamps those under 30. And that includes the US, which has long had high birthrates than most developed nations: 5 But even that is looking fragile. The 2010 census suggested that US population growth be decelerating faster than many expected. 6 However, it's probably wrong to see this as a demographic 7 competition. American living standards will be hurt by an aging and less dynamic world, even if the US does attract young workers. For decade, people took dynamism and economic growth for granted 8 and saw population growth as a problem. Now we've gone to the other extreme, and it's clear that young people are the scarce resource. In the 21st century, the US could be the slowly aging leader of a rapid aging world. 9 To Brooks this is a slow-motion disaster. Aging countries will face the burden of caring for large elderly populations without a large source of 10 young workers to draw on. But here's the thing: a Centrum Silver world may have a silver lining for the planet.