题目内容
“棉花能保温，积雪也能保持地温。据测定，新降落的雪有40%到50%的空隙，棉花是植物纤维，雪是水的结晶，很不相同，但两者都是疏松多孔的。可见，疏松多孔的东西能够保温。” 分析此例运用了何种探求因果联系的方法。说明理由并写出该逻辑方法的公式。
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为了提高测试的效率，正确的做法是______。
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By now, the idea of airline baggage charges, extra legroom at a cost, paying for food and so on, has become for travellers a bit like the pre-flight safety explanation about how seat belts work. It may annoy. Or perhaps it has become so common that it no longer elicits much response. But these transactions are helping keep the planes flying, and they illustrate a market reality increasingly faced by a wide spectrum of consumers and businesses.Efforts by airlines around the world to increase revenue apart from ticket prices have grown almost tenfold since 2008 to $22.6 billion. And, even with that, the International Air Transport Association is projecting overall global airline profits will be down in 2012 for a second successive year to about $3 billion. That"s a profit margin of just 0.5 percent, so what some see as nickel-and-diming is viewed within the turbulent airline industry as pennies from heaven. "The whole economics of the business have been an absolute disaster since the fuel crisis of 2008," IdeaWorks President Jay Sorensen explained. "Airlines are just desperate for money."The economy has ensured that this desperation is not unique to airlines or even the travel business, where hotels may look to charge for a Wi-Fi connection that Starbucks will give you for free, or charge extra fee on top of the cost of whatever the resort"s room rate is and maybe tack on a housekeeping extra charge. You see this batteries-not-included mentality elsewhere. Cellphone companies that once advertised all-inclusive services look to sell data and voice separately. Banks try to assess new fees to cover costs they once absorbed."In an industry cycle, in the beginning, when you"re in a high-growth period, you tend to see a lot of bundling, giving a lot of things at one price," Jean-Manuel Izaret said by phone. "At the other extreme, when you are in the super-mature area, you"ll have low-cost providers entering certain markets with no-frills offers. So in a mature market, where low-cost challengers have come in and undercut the prices of established players, the only option for established players is to unbundle and price every little thing separately.""Airlines are going to have to be careful of nuisance fees, like checked bags and seating, and focus instead on inventing services that have not been offered before that people value," Sorensen said. That proposition is critical. But within a company the ability to generate revenue through a service often means more resources will be devoted to improving it. So the baggage service, for example, not only has benefited from fewer checked items in the system but greater investment in that system by airlines. Charging for specific services like baggage handling lets airlines invest to provide greater reliability for those who check a bag, without passing on the cost to customers who don"t. The expression "nickel-and-diming" refers to ______
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