[单项选择]

Questions 18～21 are based on the following dialogue between two friends talking about traveling.
M: So you’re visiting San Francisco
W: Yes, I just got here the day before yesterday, and you
M: I’m a native.
W: Oh, really All the people I meet here are tourists like me. I was beginning to think that maybe there were no natives.
M: Well. San Francisco has a lot of different ethnic groups, so you might think you’re seeing a lot of foreigners. But in fact, the city has a population of about 700, 000 people.
W: What are the ethnic groups
M: Well, after whites, the largest one is blacks.
W: I thought it was Chinese.
M: It’s true that San Francisco has the largest Chinese community outside Asia. But the black people there are more than Chinese.
W: That’s interesting. Don’t most of the Chinese people live in China-town
M: Well, no, they live throughout the city, bu
A. He thinks the city is pretty.
B. He likes to talk with people.
C. He travels a lot in the city.
D. He teaches ethnic history at a university.