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?

In order to take 3 days off, you must ask      from your boss.

小明离家出走了，给妈妈留下一张字条：“我不明白你们为什么不理解我，为什么总是干涉我的自由，总让我按你们的意志去做，你们越让这样我越不愿意这样，为了自己的自由，我决定离家出走。”

如图所示A,B两细胞间突触的亚显微结构。下列相关叙述不正确的是（  ）

如图所示，a、b、c为同一种材料做成的电阻，b与a的长度相等，横截面积是a的两倍；c与a的横截面积相等，长度是a的两倍. 当开关闭合后，三个理想电压表的示数关系是  （     ）