[填空题]The world has never seen population ageing before. Can it cope Until the early 1990s nobody much thought about whole populations getting older. The UN had the foresight to convene a "world assembly on ageing" back in 1982, but that came and went. By 1994 the World Bank had noticed that something big was happening. In a report entitled "Averting the Old Age Crisis", it argued that pension arrangements in most countries were unsustainable. For the next ten years a succession of books, mainly by Americans, sounded the alarm. They had titles like Young vs Old, Gray Dawn and The Coming Generational Storm, and their message was blunt: health-care systems were heading for the rocks, pensioners were taking young people to the cleaners, and soon there would be intergenerational warfare. Since then the debate has become less emotional, not least because a lot more is known about the subject. Books, conferences and research papers have multiplied. Whether all that attention has translated into sufficient action is another question. Governments in rich countries now accept that their pension and health-care promises will soon become unaffordable, and many of them have embarked on reforms, but so far only timidly. That is not surprising: politicians with an eye on the next election will hardly rush to introduce unpopular measures that may not bear fruit for years, perhaps decades. The outline of the changes needed is clear. To avoid fiscal meltdown, public pensions and health-care provision will have to be reined back severely and taxes may have to go up. By far the most effective method to restrain pension spending is to give people the opportunity to work longer, because it increases tax revenues and reduces spending on pensions at the same time. It may even keep them alive longer. John Rother, the AARP"s head of policy and strategy, points to studies showing that other things being equal, people who remain at work have lower death rates than their retired peers. Younger people today mostly accept that they will have to work for longer and that their pensions will be less generous. Employers still need to be persuaded that older workers are worth holding on to. That may be because they have had plenty of younger ones to choose from, partly thanks to the post-war baby-boom and partly because over the past few decades many more women have entered the labour force, increasing employers" choice. But the reservoir of women able and willing to take up paid work is running low, and the baby-boomers are going grey. In many countries immigrants have been filling such gaps in the labor force as have already emerged (and remember that the real shortage is still around ten years off). Immigration in the developed world is the highest it has ever been, and it is making a useful difference. In still-fertile America it currently accounts for about 40% of total population growth, and in fast-ageing western Europe for about 90%. On the face of it, it seems the perfect solution. Many developing countries have lots of young people in need of jobs; many rich countries need helping hands that will boost tax revenues and keep up economic growth. But over the next few decades labor forces in rich countries are set to shrink so much that inflows of immigrants would have to increase enormously to compensate: to at least twice their current size in western Europe"s most youthful countries, and three times in the older ones. Japan would need a large multiple of the few immigrants it has at present. Public opinion polls show that people in most rich countries already think that immigration is too high. Further big increases would be politically unfeasible. To tackle the problem of ageing populations at its root, "old" countries would have to rejuvenate themselves by having more of their own children. A number of them have tried, some more successfully than others. But it is not a simple matter of offering financial incentives or providing more child care. Modem urban life in rich countries is not well adapted to large families. Women find it hard to combine family and career. They often compromise by having just one child. A. Intergenerational conflicts will intensify. B. need large numbers of immigrants from overseas C. People should be allowed to work longer. D. They find it hard to balance career and family. E. the current pension system in most countries could not be sustained in the long term F. The employers are unwilling to keep older workers G. politicians are afraid of losing votes in the next electionIn its 1994 report, the World Bank argued that ______.