单项选择题

Questions 17—20 are based on the following talk on booking tickets. You now have 15 seconds to read questions 17—20.
Why does Mr. Cotton call

A．He calls to cancel his reservation.
B．He calls to change his ticket.
C．He calls to check his ticket.
D．He calls to cancel his reservation and make another.

Questions 17—20 are based on the following talk on booking tickets. You now have 15 seconds to read questions 17—20. Why does Mr. Cotton call

Questions 17—20 are based on the following talk on booking tickets. You now have 15 seconds to read questions 17—20.
Why does Mr. Cotton call