若m＞n，下列不等式不一定成立的是（   ）

下列说法正确的是（   ）

①具有规则几何外形的固体一定是晶体      ②NaCl晶体中与每个Na⁺距离相等且最近的Na⁺共有12个

③非极性分子中一定含有非极性键          ④晶格能由大到小：NaF＞NaCl＞NaBr＞NaI

⑤含有共价键的晶体一定具有高的熔、沸点及硬度      ⑥s﹣s σ键与s﹣p σ键的电子云形状相同

⑦含有π键的化合物与只含σ键的化合物的化学性质不同  ⑧中心原子采取sp³杂化的分子，其立体构形不一定是正四面体．

根据短文内容理解，选择正确答案。    Hi, I'm Brian. This is the photo of my family. My grandfather is with glasses. He has little hair. The one standing next to him is my uncle. He is wearing a cap. My grandmother has gray hair. She is a kind woman. She is holding my younger brother. He has short curly hair. The woman standing behind me is my mom. She has straight brown hair. There is a little girl sitting on the table. Her name is Cathy. She is my sister. She is wearing a green T-shirt and a pair of green socks. It's her favorite color. Which one is my father? Well, he is wearing glasses, too. He is in brown shorts and brown shoes. His name is Sam. Now, do you know where he is?

耶鲁大学毕业，现任湖南衡山福田铺乡白云村大学生村官，黑土麦田公益联合发起人。大学毕业时，秦飞选择回祖国农村服务。改善灌溉系统、建现代化敬老院，为乡村师生开展信息化教学……他说成功不可能一夜间发生，“必须脚踏实地一步步去做。” 秦飞的事迹告诉我们（    ）

①用认真、勤劳、善良、坚持、责任、勇敢书写自己的生命价值

②当我们将个体生命和他人的、集体的、民族的、国家的命运联系在一起时，生命便会从平凡中闪耀出伟大

③每个人通过自己的坚韧和努力，都可以获得生命的意义

④生命的意义来自我们对生活的索取

若$\sqrt{x-1}$+$\sqrt{x+y}$=0，则x²⁰¹⁵+y²⁰¹⁶的值（　　）