单项选择题

You will hear four dialogues or monologues. Before listening to each one, you will have 5 seconds to read each of the questions which accompany it. While listening, answer each question by choosing A, B, C or D. After listening ,you will have 10 seconds to check your answer to each question. You will hear each piece ONLY ONCE.
Questions 11~13 are based on the following dialogue between two passengers. How often is the bus scheduled to pass their stop

A. Every ten minute.
B. At twenty to one.
C. Every thirty minute.
D. Once a day.