阅读理解
Several days ago，Brenda had a car accident．As a result．one of her legs had to be cut off.She became quiet and didn't talk to anyone．
"I wish I could bring her friends to visit her," Brenda's mother said to the nurse．"It's just too long a bus trip．""Don't worry," the nurse smiled．"I have a plan．"
Later that day, the nurse told Brenda it was moving day．Before Brenda could refuse，the nurse had taken her to another room filled with colourful flowers．"Here's your new roommate，Annie，"the nurse told a dark-haired teenager(青少年)on the other bed．
Annie smiled．After the nurse left．she hopped (单脚跳)out of her bed and sat at the other end of Brenda's．
"I lost one of my legs from bone cancer (骨癌)，"she said．"What happened to yours?"Brenda was so surprised that she couldn't say a word．"You're ▲ ．"Annie continued．"You've still got your knee．They had to take mine．"
Annie hopped back to her bed．"l'd like to talk with you，but my friends are coming any time now，so I have to get ready," Annie said when she reached up and took off her hair!Her head was completely bald(秃的).
"Oh，I forgot to tell you，the medicine they gave me to kill(杀死) the cancer also killed my hair,"Annie said．
When Annie's friends came．she introduced Brenda to them all．Before long，Brenda started talking with Annie and her friends．They didn't make her feel like a freak (怪人) at all!By the time the nurse asked·the visitors to leave．Brenda feIt great．
The girls talked into the night and shared their dreams with each other．When it was time to go to bed，Brenda said，"Good night，Annie．Can't wait till morning．"
根据材料内容选择最佳答案。
的值域为（ ）