I love seeing Europeans line up in airports to applaud arriving refugees. But humanitarianism   will not guide policy for long. We liberals need to argue from Europe's self-interest: our continent has the need, the space and the ability to accept people. Many European countries are gradually turning into old people's homes. Germany, Italy, Spain and others have some of the lowest birth rates in human history. It is predicted that about one-third of their populations will be aged over 65 in 2050. Germany needs to import at least 350,000 people a year to keep its workforce stable. Suddenly, young ambitious workers are pouring into the country as if called by a genie   with a lamp. No wonder Angela Merkel, German Chancellor, has been more welcoming than David Cameron, British Prime Minister. But all over Europe, carers for old people are already in need. Norway found oil under the seabed but it would have been better off if it had discovered 50,000 nurses there instead. Many rightwingers think we have reached our limits. This feeling is widespread. And it's true that Western Europe is one of the most densely populated regions on earth. Indeed, density has long been Europe's unique selling point: with so many people of different nations closely packed together, we have always traded goods and exchanged ideas fast. That's why the scientific revolution of the 16th and 17th centuries happened here. But we have plenty more room. Many European cities aren't dense enough. Now east Germany, north-western Spain and gorgeous mountain villages in Italy are losing people. Lots of cities have unused industrial land. Humans inhabit a slice of the EU's territory. Only about 2.5 per cent of the EU's land is used for housing, estimates the European Commission. By contrast, a whopping 43 per cent was used for agriculture in 2009, it says. That's too much. We could turn more land into forest or into green landscapes where people can relax and play. Making that transition is feasible because we now use agricultural land inefficiently. Migrants often spend years locked up together in serious government-funded "migrant centers". However, the way to learn a new country's language, make friends and find work is to live with a local. This crisis has shown that lots of Europeans are willing to take refugees into their homes. After Iceland's government said it could take only 50 Syrian refugees, many Icelanders came forward offering to take a far greater number into their own homes. People aren't just sitting around waiting for government to do something. We need migrants, and we can accommodate them. If opponents just don't like foreigners, they should say so instead of pretending to be hardheaded pragmatists  . Which of the following statements is TRUE?
No other region is more densely populated than Western Europe. Density has become Europe's most outstanding characteristic. All European cities are not crowded together in great numbers. Large quantities of unused industrial land will turn into forest.