阅读理解。
Many large cities in the United States have an area called Chinatown. Each of them was set up by people
who came from China. For example, Chinatown in San Francisco, California, began in the 1840s. The Chinese
immigrants (移民) came to America to look for gold. Then the area they lived in later became known as
Chinatown.
Chinatowns were also setup in cities in the western states of Oregon and Washington during the middle of
the 19th century. Many Chinese immigrants in these areas helped build the first railroad system across the
United States. However, after the work ended in 1869, many Chinese moved to the eastern and middle parts of
the United States.
Chinatowns can also be found in cities outside the United States. For example, the first Chinese immigrants
in London arrived in the late 18th century. They were men who worked for the East India Company. Later, the
Chinese immigrants opened small stores and restaurants there.
Today, many people visit Chinatowns. They have special Chinese gates and walking areas for visitors.
Chinatowns around the world are not only places where Chinese people live and work. They are also places
where visitors can learn more about Chinese culture and traditions.
1. In the 1840s, a large number of Chinese people went to America to _____.
A. look for jobs
B. look for gold
C. build Chinatowns
D. build the railway
2. According to the passage, Chinatown in Oregon was set up about _____ years ago.
A. 100
B. 160
C. 200
D. 300
3. According to the passage, Chinatown can also be found in _____ outside the United States.
A. London
B. Oregon
C. Washington
D. San Francisco
4. Visitors come to Chinatowns because they want to _____.
A. taste the food there
B. do shopping there
C. make some Chinese friends
D. learn more about Chinese culture
5. What's the best title of the passage?
A. The History of Chinatowns
B. The Visitors to Chinatowns
C. The Culture about Chinatowns
D. The Immigrants in Chinatowns
2NO2，其中NO的物质的量随时间的变化如下表