下列说法不正确的是
A．常温下，氧气与所有金属都能反应
B．棉花属于天然有机高分子材料
C．结晶水合物属于纯净物
D．中和反应一定有盐和水生成
答案：A
A、常温下，氧气不与金等反应，故A说法不正确；
B、棉花属于天然有机高分子材料，故B说法正确；
C、结晶水合物属于纯净物，故C说法正确；
D、中和反应是指酸和碱反应生成盐和水的反应，故D说法正确。
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| You'll see a new doctor at a hospital near London if you go there. He's very clever, 1 he never speaks. He can work 24 hours a day and never gets 2 . He's one metre tall and has a face 3 a TV screen. He is Dr Robot. Doctors 4 need to ask their patients a lot of questions. 5 doctors can only spend a few 6 with each patient. But Dr Robot can ask a paitent for an hour if it is 7 . With the help of Dr Robot, a human doctor can 8 a lot of useful information when he meets his patient. 9 can Dr Robot do this? A computer tells him to do. Dr Robot can do a lot of things people can do, though he can't completely 10 the place of huan doctors. | ||||
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