A．They are brought up in cultures where modesty is highly valued.
B．They think it is a shame to speak highly of their own culture.
C．They are challenged by people from other cultures.
D．The values of humility is looked down by those with higher status.

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