________ is tired and thirsty.

阅读下面的漫画，给漫画拟一个标题，并说明漫画的内容。

已知某水溶液中大量存在H⁺、Mg²⁺、K⁺、NO₃^﹣、Cl^﹣中的四种离子，且存在的各离子具有相同的物质的量，则不能存在的离子是（　　）

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?

X,Y,Z,W为周期表中前20号元素中的四种，原子序数依次增大，W,Y为金属元素，X原子的最外层电子数是次外层电子数的3倍，Y,Z位于同周期，Z单质是一种良好的半导体．W能与冷水剧烈反应，Y,Z原子的最外层电子数之和与X,W原子的最外层电子数之和相等．下列说法正确的是（    ）