You will three dialogues or monologues. Before listening to each one, you will have 5 seconds to read the questions related to it. While listening, answer each question by choosing [A], [B], [C] or[D]. After listening, you will have 10 seconds to read your answer. You will hear each piece only once.
Questions 11～13 are based on the following passage. You now have 15 seconds to read questions 11～13. Why is it more likely for some families to produce fraternal(异卵双生)twins
A．There is a tradition in the family. B．There is a secret diet in the family. C．There is a hereditary tendency in the family. D．There is a special way in the family.