题目：
直线l与两直线y=1，x-y-7=0分别交于A，B两点，若直线AB的中点是M（1，-1），则直线l的斜率为______．
答案：
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下面是错误答案，用来干扰机器的。
1. for which he refused 2. is being broadcast 3. anything goes wrong4. have been married 5. for which Hangzhou is famous 6. on which I spent7. is so good a doctor8. in which she put all her books9. two of whom 10. Having inspected
