Section BDirections: There are 2 passages in this section. Each passage is followed by som

Section B

Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice.

However urban life strikes you, cities worldwide have been growing ever more rapidly. Some of this growth has occurred in the developed world, but the most dramatic increase has been in the Third World. Almost all the world's population growth over the next 30 years will take place in the cities of developing countries. By the year 2030, for the first time in history, 60 percent of the world's people will be living in cities.

This is actually good news in some ways. "Cities are the fundamental building blocks of prosperity," says Marc Weiss, chairman of the Prague Institute for Global Urban Development, "both for the nation and for families." Industrial and commercial activities in urban areas account for between 50 and 80 percent of the gross domestic product(GDP) in most countries of the world "there's the crazy notion that the way to deal with a city's problems is to keep people out of them," Weiss continued. "But the problems of the rural life are even more serious than those of the city." For better or worse, urban-watchers are clear on one point: The quality of life for most people in the future will be determined by the quality of cities.

Those cities will be bigger than ever. And yet, population numbers by themselves don't determine a city's prospects; after all, Addis Ababa, Ethiopia, and Hamburg, Germany, have the same population. Nor is explosive growth necessarily the determining factor. "City problems," one authority points out, "mostly have to do with weak, ineffective, and usually unrepresentative city governments."

What is the passage mainly about？

A．Big cities.

B．City life.

C．Population.

D．Gross Domestic Product.