已知数列$\left\{a_n\right\}$为等比数列，且$a_4·a_6=2a_5$，设等差数列$\left\{b_n\right\}$的前n项和为$S_n$，若$b_5=2a_5$，则$S_9$=(   )

阅读下面三段古文语段，回答问题
        甲文：郑人有欲买履者，先自度其足，而置之其坐。至之市，而忘操之。已得履，谓曰：“吾忘持度！”返归取之。及返，市罢，遂不得履。人曰：“何不试之以足？”曰：“宁信度，无自信也。”
        乙文：楚人有涉江者，其剑自舟中坠于水。遽契其舟，曰：“是吾剑之所从坠。”舟止，从其所契者入水求之。舟已行矣，而剑不行。求剑若此，不亦惑乎！
        丙文：余常于土墙凹凸处、花台小草丛杂处，常蹲其身，使与台齐，定目细视。以丛草为林，以虫蚁为兽，以土砾凸者为邱，凹者为壑，神游其中，怡然自得。

如图是印度不同季节季风活动图，回答下列问题：

    After thirty years in the classroom, I have come to realize that teacher's behavior can make a world of difference for a child. This is one such 1.

    While I was attending a party being 2 at a high school one evening, I looked around and noticed a young girl who looked 3. I thought she had been a(n) 4 of mine. I tried to remember her 5, but I couldn't. I felt so frustrated (沮丧的), 6 I have always been able to 7 former students.

    Her eyes met mine and she threw her 8 around me and said, “Mrs. G, it's me, Sarah, and I'm still 9!” The memories 10. You see, Sarah was 11 a student in my classroom. Sarah's mother had abandoned (遗弃) her, and her father had 12 her. She was sent to live with her grandparents the year I 13 her. Sarah was angry, often in 14 and often in the office.

    It was during one of those 15 visits that I first met her. She was writing. I introduced myself to her and asked her 16 she was writing. Sarah shared her story with me. I knew it was healing (康复) for her to put her 17 on paper. Every morning before school she would come into my classroom and we would work on her writing skills.

    Our conversation that evening was filled with 18. She expected to go to college. Driving home, I could not help but 19 the impact (影响) for both good and bad that teachers have upon their students. Taking the time to 20 with a child has the power to change that child's life. That's why I teach.

***历史上最大冤案的受迫害者是(   )