A、Playing the piano. B、Playing a CD. C、Singing a song. C贝蒂在唱歌。选项[C]Singing a song．正确。

W: Mike! Could you tell Tom to mm down the TV? It’s noisy!
M: Yes. I’ll tell him to mm it down.
Q: What will Mike do?

M: What are you singing, Betty?
W: It’s called Summer Time. Have you ever heard it?
M: Never.
Q: What is Betty doing?