阅读理解：
When you pick up your incoming luggage at an airport, you may tip the man who takes it to the taxi or airport bus. He usually expects 35cents a bag for his service. In come cities the taxi that take you to your hotel may have one meter that shows the cost of the trip and another that shows a fixed charge, usually about 20 cents, for extra. In some cities the taxi driver may expect a tip in addition to the extra, especially if he carries your suitcase. If no extra is charged, a tip is usually given. Hotels generally do not make a service charge, though there are places where one is added. It is customary, however, to give something to the porter who carries your suitcases and shows you to your room. In case of doubt, 35 cents for each bag he carries is satisfactory. In a restaurant you generally leave about 15 percent of the bill in small change on that table as a tip for the person who has serves you. A service charge is generally not included except in some of the larger, more expensive places. If the order is small - a cup of coffee at a lunch counter, or something of the sort - a tip is not usually expected.
A) is consistent throughout the world.
C) is consistent in large towns in the USA.
2. According to the passage, the following are the people one may tip EXCEPT
B) taxi drivers.
D) cleaners.