单词：angle back pressure valve
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With the late winter storm bearing down on Massachusetts, one group of plucky individuals in Milton, Massachusetts, got together to help out their neighbors across the road. From PBS station WGBH, Cristina Quinn has the story. What happens when the c
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This is Scientific American's 60-second Science. I'm Karen Hopkin. This will just take a minute. If you were a bird, how big could you be? Well, an ostrich can weigh 400 poundsbut it cant get off the ground. So what if you want to fly? University of
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Molting Molds Flying Bird Size Limit A study in the journal Public Library of Science Biology finds that it's the rate at which flying birds can replace their flight feathers that determines how big they can grow and still get off the ground. Karen
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Humans Need More Sleep in the Winter: Say What? During this time of year, its hard to not be jealous of the various squirrels, hedgehogs, possums, chipmunks, bats, skunks, lemurs, and other small mammals that lower their body temperatures and their m
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小学英语写作范文：感恩父亲 Dear Dad: You have worked hard! In the past, I am always afraid to you and positive dialogue. Every time something was always afraid to tell you. Because when you face the total serious. Today to take this oppo
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