[originaltext] I travel a lot, and I find out different "style" of direction

I travel a lot, and I find out different "style" of directions every time I ask "How can I get to the post office?"
    Foreign tourists are often confused in Japan because most streets there don’t have names: in Japan, people use landmarks in their directions instead of street names. For example, the Japanese will say to travelers, "Go straight down to the corner. Turn left at the big hotel and go past a fruit market. The post office is across from the bus stop."
    In the countryside of the American Midwest, there are not usually many landmarks. There are no mountains, so the land is very flat; in many places there are no towns or buildings within miles. Instead of landmarks, people will tell you directions and distances. In Kansas or Iowa, people will say, "Go north two miles. Turn east, and then go another mile."
    People in Los Angeles, California, have no idea of distance on the map; they measure distance in time, not miles. "How far away is the post office?" you ask. "Oh," they answer, "it’s about five minutes from here." You say, "Yes, but how many miles is it?" They don’t know.
    It’s sure that a person doesn’t know the answer to your question sometimes. What happens in such a situation? A New Yorker might say, "Sorry, I have no idea." But in Yucatan, Mexico, no one answers "I don’t know". People in Yucatan believe that "I don’t know" is impolite. They usually give an answer, often a wrong one. A tourist can get very, very lost in Yucatan!
Questions 16 to 19 are based on the passage you have just heard.
16. What do the Japanese usually do when a tourist asks them the way to a certain place?
17. What is the place where people measure distance in time?
18. What do we learn about people in Yucatan?
19. What can we infer from the passage?