In this section, you will hear several passages.
Listen to the passages carefully and then answer the questions that
follow. Questions 11 to 13 are based
on the following passage. At the end of the passage , you will be given 15
seconds to answer the questions. Now, listen to the
passage. What is the original meaning of the tip
A．It is to reward the efforts of good service. B．It is a promise of on-time service. C．It is used to reduce uncomfortable feelings of inequality. D．It serves no useful function.