根据问句,选择适当的答语。 A. She's taking pictures. B. I'm talking to my friend. C. He's playing with his car. D. No, I'm not. [[QOrDeR]]What are you doing? (____) 【小题2】What is Sam doing? (____) 【小题3】What is she doing? (____) 【小题4】Are you writing a letter? (____)