Read and choose. (根据上下文,找出适当的句子,将其标号填在横线上) A. Hold on, please. B. I'm doing my homework, now. C. Who's that? D. What is he doing? E. It's Mary here. Mary: Hello. Helen: Hi. This is Helen speaking. Mary: 1. ________________ Can I speak to your brother, Peter? 2. ________________ Helen: He is reading a book. 3. ________________ Peter, it's for you. Peter: OK. I'm coming. Thank you. It's Peter here. 4. ________________ Mary: This is Mary. 5. ________________I have a question.