Questions 1 to 3 are based on the following conversation. At the end of the conversation, you will be given 15 seconds to answer the questions.
Now, listen to the conversation.
How does the man feel about the woman’s decision

A．explain the derivation of the word "tip".
B．illustrate why difficult customers give bad tips.
C．put forward reasons for a salary increase.
D．indicate how one can get better service.

A．How canals are constructed.
B．Common types of canal boats and barges.
C．The world’s largest canals.
D．How canals are used and classified.