已知圆C₁：x²+y²=b²与椭圆C₂： $\frac{x^2}{a^2}+\frac{y^2}{b^2}$ =1，若在椭圆C₂上存在一点P，使得由点P所作的圆C₁的两条切线互相垂直，则椭圆C₂的离心率的取值范围是（   ）

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    Hi, I'm Gina．I have my birthday on the 12 th of March．It is in spring and the weather is usually warm．My parents always say“Happy birthday”and give me gift(礼物)on the morning of my birthday．I enjoy getting them．I usually have a birthday party at home．My relatives(亲戚)and friends come to the party．

    My birthday party is on Sunday this year．I get up early in the morning．My father and I go to the supermarket to buy something we need for the party．My mother is at home．She cleans the house,makes cakes and prepares for(为……做好准备)the party．

    At about four o'clock my relatives and friends come and I am happy to see them．My relatives buy a dress，a bag and a computer…game for me．My friends bring flowers，books and candies．

    My mother brings us a cake with 13 candles on it．Everyone sings“Happy Birthday to You”and I blow all the candles out．Then we sing，dance，play games and talk about our life．

    I enjoy my birthday party and everyone has a great time at my party．

根据材料内容简要回答下列问题。

①科学家此前就发现，普通鱼类可以通过内耳中耳石上的生长轮来判断年龄。

②龙虾的具体年龄一直是个谜，甚至有人认为它活到100岁都没有问题。

③科学家最近还发现，龙虾身上也有“年轮”，可以计算出它的年龄。

④研究人员发现，这类物种的生长轮可以在它们连接身体和眼球部分的眼柄中找到。

⑤我们通过树木的年轮可以判断其年龄，那么，动物尤其是我们所知甚少的海中动物呢？

7＋6=____

14－8=____

7＋9=____

18－8=____

9＋7=____

18－9=____

8＋8=____

13－6=____

马克思曾指出，德意志帝国实质上是一个“以议会形式粉饰门面，混杂着封建残余、已经受到资产阶级影响、按官僚制度组织起来，并以警察保卫的、军事专制制度的国家。”对这段话理解正确的是（     ）

①德意志帝国具有资本主义色彩     ②德意志议会的权力很小

③德意志帝国的统治不稳固         ④德意志皇帝的权力很大