Question 21 is based on the passage you have just heard.

听力原文：

    Katherine loved Facebook. With Facebook she could stay connected with her family no matter how far away they were. She could see their photos and read their status updates. With Facebook, she could keep her relatives up-to-date on what she was doing.（19）Another thing Katherine loved about Facebook was that she didn’t have to think about time zones when updating family. Whenever she called her parents or other relatives, she always had to think about the time difference so that she wouldn’t wake someone up or call when she knew they were at church. Facebook was so convenient.

    When Katherine joined Facebook, some of her classmates at high school started to add her as a friend. At first, this didn’t bother her.（20）She loved learning about the success of people she knew when she was just a teenager. She loved finding out people were getting married, having babies, and traveling.

    （21）Soon however, Katherine found herself comparing herself with the people she was reading about on Facebook. It began to make her feel bad that some people seemed to be doing so much better than she was. She was also spending a lot of time on Facebook. It took a lot of time and energy to keep up with everyone’s status updates.

    Katherine started to think. She looked at the list of over 500 friends she had on Facebook and realized some of them were not really friends at all.

21. What made Katherine feel bad about herself later on?

解析：D。本题目为细节题。问题为：什么使得Katherine随后对自己的感觉很不好？出题点位置为转折处。根据原文“It began to make her feel bad that some people seemed to be doing so much better than she was.”，可见她开始感觉不好，是因为其他人看起来做得要比她好。故正确答案为D）She didn’t seem to be doing as well as her Facebook friends（她感觉自己没有和其他朋友做得一样好）。