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. What does the passage tell us about American rivers
A．All the rivers used to be very dirty. B．About one in three of the rivers are polluted. C．All the rivers are unsafe and smelly. D．Kids will go to the river bank to cam.