某化学兴趣小组用图1所示装置进行探究实验，以验证产物中有乙烯生成且乙烯具有不饱和性．当温度迅速上升后，可观察到试管中溴水褪色，烧瓶中浓H₂SO₄与乙醇的混合液体变为棕黑色．

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    Once (从前) a man stole (偷) one of Washington's horses. Washington went with a policeman to get back the horse. But the man didn't give the horse to Washington. He said it was his horse. Washington put his hands on the eyes of the horse and said to the man, “If (如果) this is your horse, you must tell us in which eye he is blind (瞎的).”“In the right eye!” the man said. Washington took his hand from the right eye of the horse and showed the policeman that the horse was not blind. “Oh, I made a mistake (弄错了),” said the man. “He is blind in the left eye.” Washington then took his hand from the left eye of the horse. It was not blind in the left eye either (也不).“I made another mistake (又弄錯了 ),” said the man. “Yes,”said the policeman, “and you know the horse is not yours. You must give it back to Washington.”