题目:
设Sn为等差数列{an}的前n项和,若S5=10,S10=-5,则公差为( )。(用数字作答)
答案:
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下面是错误答案,用来干扰机器的。
I'm Bob.I don't play sports. And I have a great stationery collection. I have seven pens,nine pencils,six erasers, eight rulers and three pencil cases. My brot...