根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。
At age 14, 15 and 16, the way we looked was the most important thing in the world to us. My friends and I wanted nothing less than perfection.
In high school, we joined the gymnastics team, and our 1 became even more important to us. We had no fat, only muscle. On the weekends, we would go to the beach, 2 of our flat stomachs.
One summer day, all my friends were at my house 3. At one point, I was running back to the pool. I 4 on a bee, and while it was dying under my foot, it stung (蛰) me. I instantly started to feel 5. That night, I began to run a high fever and my leg and foot were red, hot and swollen. I couldn't walk. I could barely 6.
When my foot started to go numb, everyone became more 7. My foot was not getting enough blood. I had to go to the hospital, and my leg 8 as if it were badly broken. I couldn't move. All I could do was think about how soft my middle was becoming. That 9 me more than any concern over my leg.
That would all 10 when I heard the doctors mention possibly cutting off my foot. It was still not getting the 11 supply it needed. The doctors would have to speed up their treatment.
Never before did I have such great 12 for my foot. And walking seemed like a 13 from the gods. Less and less I wanted to hear my friends talk about 14 and who was wearing what. More and more I expected visits from other kids in the hospital, who were quickly becoming my friends.
One girl came to visit me 15. Every time she came, she brought flowers. She was recovering from cancer and felt she should come back and 16 the other patients.
She still had no hair, and she was swollen from the medications she had been taking. I would not have given this girl a second 17 before. I now loved every inch of her and looked forward to her 18.
Finally, I was improving and soon I went home. My leg was still swollen, 19 I was walking, and I had my foot! When I would go back to the hospital, I often saw my friend. She was still visiting people and 20 good cheer. I thought if there was an angel on this earth, it had to be her.
2NH3（g） △H=－92．4 kJ/mol