如图表示某生物的DNA分子结构的片段，下列有关叙述正确的是（    ）

在含有Fe³⁺、Fe²⁺、Cu²⁺的溶液中加入铁粉，充分反应后，固体残渣用盐酸处理有气体放出，则与铁粉反应后的溶液中最多的离子是

函数y=a^x﹣2+1（a＞0且a≠1）的图象恒过定点____．

2和8的等差中项与等比中项的积是____．

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?