Hi, I'm Brian. This is the photo of my family. My grandfather is wearing(戴着) glasses. He has little hair. The one next to him is my uncle. He is wearing a cap. My grandmother has gray hair. She is a kind woman. She is holding(抱着) my younger brother. He has short hair. The woman standing behind me is my mom. She has 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?

等式左边加一个数，右边减去同一个数，所得结果仍然是等式．

在正方形ABCD中，点E，F分别在边BC，CD上，且∠EAF=∠CEF=45°．