已知两个变量x、y之间的关系为y=（m﹣2）$x^{m^2-2}+x-1$，若x、y之间是二次函数关系，求m的值．

    One of my favourite cartoons are Pleasant Goat and Big Big Wolf. I have seen many cartoons. Because Pleasant Goat and Big Big Wolf is my favourite. I like it because it's much modern than another cartoons. The story is about a clever goat. It is the hero of the story. It's clever and brave. It always finds ways help other goats run away from Big Big Wolf. It leads other goats fighting the Big Big Wolf. They protect each other and work hardly together and they are always successful. The cartoon is very interested. I can't always help to laugh. If you haven't saw it yet, please don't miss it. 

如图，已知△ABC中，∠ABC＝45°，F是高AD和BE的交点，CD＝4，则线段DF的长度为（　　　）

下列气体有颜色和有刺激性气味的是（　　）

    One of my friends Fred did very little work when he was a student. He spent more time drinking in bars(酒吧) than working in the library. Once, we had to take an important exam. The exam had a hundred questions. To each question we had to write "Right" or "Wrong". The night before the exam, Fred was watching TV and drinking. He usua1ly worried a lot the night before the exam. But on that night he looked quite quiet. He told me what he would do." It's very easy," he said to me, "There are a hundred questions and I have to get fifty right answers to pass the exam. I'll bring a coin(硬币 )with me and throw it to decide(决定)answers. I'm sure I'll get half the questions right in this way. "During the exam, Fred sat down and really threw the coin for half an hour when he was writing down his answers. Then he left half an hour before the others. The next day he saw the teacher on the playground. "Oh, good, Mr. Wu," he said, "Have you checked the papers? Have I passed?" The teacher looked at him and smiled, "Ah, it's you, Fred. A moment, please." Then he put his hand into his pocket and took out a coin. He threw it into the air, caught it in his hand and looked at it. "I'm very sorry, Fred, you failed."

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