补全对话。 A: Excuse me, Miss Black. 1______. B: Not very big, but I think it's not fairly small. I have two brothers. The elder one is married. A: Do your brother and his wife have any children? B: Yes. 2 ______. A: Boy or girls? B: A boy and a girl, so I have a niece and a nephew. A: Can a sister and a brother be twins? B: It's uncommon but possible. In China, there are still quite a lot of large families, aren't there? A: 3 ______. Thanks to the 'one-child' policy (政策), very few families now have more than one child. 4 ______. B: 5 ______. Is your family large? A: No, I have only one sister, but my grandparents are living with us. B: In America, children often move away from home when they are just 18 or 19. It's sad. Many children live far away from their parents. A: In China, too. More and more young people live far away from their parents when they are married. A. How about your family? B. My sister-in-law gave birth to twins last March. C. Are your married? D. So more and more families are becoming richer and richer. E. Do you have a big family? F. I agree with you. G. I don't think so.