题目内容
多伦多大学的生态学家们在对使用五大湖中两个湖的10处沙滩的8000多人的调查研究中发现：游泳的人中呼吸道疾病和胃肠疾病的患病率达96%，而没有游泳的人这两类病的患病率为95%。从上述数据能最恰当地得出如下哪一结论？
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关于工艺美术运动说法不正确的是()。
Backpacks are convenient. They can hold your books, your lunch, and a change of clothes, leaving your hands free to do other things. Someday, if you don't mind carrying a heavy load, your backpack might also power your MP3 player, keep your cell phone running, and maybe even light your way home.
Scientists from the University of Pennsylvania in Philadelphia and the Marine Biological Laboratory in Woods Hole, Mass., have invented a backpack that makes electricity from energy produced while its wearer walks.
The backpack's electricity-creating powers depend on springs used to hang a cloth pack from its metal frame. The frame. sits against the wearer's back, and the whole pack moves up and down as the person walks. A mechanism with gears collects energy from this motion and transfers it to an electrical generator.
Surprisingly, the researchers found, people walk differently when they wear the springy packs. As a result, wearers use less energy than when lugging regular backpacks. Also, the way the new packs ride on wearers' backs makes them more comfortable than standard packs, the inventors say.
The backpack could be especially useful for soldiers, scientists, mountaineers, and emergency workers who typically carry heavy backpacks. These people often rely on global positioning system (GPS) receivers, night-vision goggles, arid other battery-powered devices to get around and do their work. Because the pack can make its own electricity, users don't need to give up space in their packs to lots of extra batteries.
For the rest of us, power-generating backpacks could make it possible to walk, play video games, watch TV, and listen to music, all at the same time. Electricity-generating packs aren't on the market yet, but if you do get one eventually, just make sure to look both ways before crossing the street!
The first paragraph hints (暗示) ______.
投资项目外汇效果指标主要是()。
开辟了建筑形式新纪元的是()建造的()。
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