The general tone of the passage is one of ______.

A．Waiters and waitresses usually get low wages.
B．A ＄3.00 tip is usually expected for a meal of ＄20. 00.
C．Waiters and waitresses often gel best tips from customers they work most for.
D．Good tipping can help customers get quick servic

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