A. classification B.... move to the cities.
举一反三
- How many cities<br/>will have air quality monitoring systems installed by the end of this<br/>year?() A: 42 cities. B: 220 cities. C: 150 cities. D: 262 cities.
- Many Americans want to have their homes outside the cities and their jobs in the cities.
- Why did many people move to the cities Many people moved to the cities to .
- Why did people first move to cities?
- Why are Boston and Chicago mentioned A: To demonstrate the development of big cities. B: To exemplify cities with and without mass transportation C: To show mass transportation changed many cities. D: To contrast their rate of growth and development.