1. 实验下学参加各个课外小组的男、女生人数统计图如下，看图回答问题。

1. （1）数学组的男生比女生（ ____  ）（填“多”或者“少”）。
   
2. （2）参加（ ____  ）组的人数最多。
   
3. 

阅读短文，选择合适的答案。

    I study at Yu Hong Primary School in Guangzhou. I have forty-seven classmates (同学). Twenty-three are boys and twenty-four are girls. Our classroom is a nice one. It's very big. There are four windows and two doors in it. We have a big blackboard and a small one. The big one is for our teachers and the small one is for us. Mr. Li is our Chinese teacher. He is an old man. We don't like him at all. But Miss Chen, our English teacher, is a young woman. She is very nice. We all like her very much. So we like English the best. We often play basketball with Miss Chen.

那么函数解析式为 $y=2x^2+1$ ，值域为 $\left\{1,5\right\}$ 的“孪生函数”共有（    ）．