下列四个函数中，一定是二次函数的是（　　）

   A little girl thought she was not as beautiful 1other girls,and nobody liked her. So she was always 2  and didn’t like to talk to others.3 ,one day,her mother gave her a beatiful hair clip. When she wore it,she looked4 than before. She decided5  it to school.
   On her way to school, she found that everyone she saw smiled at her. Most of them said “Hello” to her, but this 6 happened before. She thought that beautiful hair clip brought them all. She was so happy about all of the great things. Although she didn't  7 her classmates about her beautiful hair clip, they want to know what happened to her.8 she went back home, her mother asked her, “Did you know you 9 your hair clip? I found it at the door this morning.”
   She understood that she didn’t wear the hair to school at all.
   It was not important what we wear or how we look. The most important thing is10 we think of ourselves.

解释下列诗句的意思。

①独钓寒江雪  ②千山鸟飞绝