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Unit 3 Life in the future Ⅰ.阅读理解 (2016·广东四校第一次联考) See a cellphone cover that you like on Taobao? Forget about placing an order, paying the bill online and waiting for days for it to be delivered to you. In the near future, you'll be able to get it in minutes just by hitting “print” on your computer. You might find it hard to believe that you could actually “print” an object like you would a picture. But it is not that hard to understand how it would work. Just as a traditional printer sprays (喷) ink onto paper line by line, modern 3D printers spread material onto a surface layer by layer, from the bottom to the top, gradually building up a shape. Instead of ink, the materials the 3D printer uses are mainly plastic, resin(树脂) and certain metals. The thinner each layer is—from a millimetre to less than the width of a hair—the smoother and finer the object will be. This may sound like a completely new technology, but the truth is that 3D printing has been around since the late 1980s. Back then, it was barely affordable for most people, so few knew about it. Last year, though, saw a big change in the 3D printing industry—printers became much cheaper. For example, 10 years ago a desktop 3D printer might have cost ￡20, 000, while now they cost only about ￡1, 000, according to the BBC. | 
