阅读上面短文，然后判断句子正( A )误( B)。
     A man saw a boy standing beside a lake with a mirror (镜子).“Excuse me,” he said, “but could you tell me what you're doing?”
   “I'm fishing.”
   “With a mirror? Could you tell me how it works?”the man asked.
   “OK, but I want five dollars.”
     The man wanted to know the secret very much, so he handed the boy the money.“Now show me how it works,” he said. “Well”, the boy began, “you hold (拿) the mirror towards the water, and when a fish goes by, the sunlight in the mirror gives him a surprise. He stops and doesn't know what to do, and then you catch him at once. ”The man was surprised, “Can you really catch fish with the mirror? How many did you catch?”
   “You're the fifth today!” replied the boy.

若圆x²+y²﹣2kx+2y+2=0（k＞0）与两坐标轴无公共点，那么实数k的取值范围为（   ）

请阅读下面材料，回答问题。

       蓝鲸，是一款俄罗斯死亡游戏，游戏的参与者在10至14岁之间。完全顺从，游戏组织者的摆布与威胁，已有130多名俄罗斯青少年因此自杀。这款游戏籍由网络，从俄罗斯传到世界其他国家，包括中国，引起了我国政府高度重视，多地公安网警通过官方微博发布相关提示，呼吁公众抵制“蓝鲸”死亡游戏，并及时举报。

计算题

已知函数f（x）=log_a $\frac{2-x}{b+x}$ （0＜a＜1）为奇函数，当x∈（﹣2，2a）时，函数f（x）的值域是（﹣∞，1），则实数a+b=____．