Since the beginning of the year, smog (霧霾) has covered parts of North China. In January, Beijing saw only five days without smog. The rising PM2.5 readings terrified many people, and some health experts said that whenever the smog gets serious, hospitals receive more patients suffering acute respiratory (呼吸系統) and heart diseases.

Later, news of polluted underground water in some provinces scared people who wondered whether the water they drink is safe.

So the need to emphasize environmental protection while developing the economy is heard everywhere.

Smog is especially a common concern. As a popular online post said, air may be the only thing that is equal for everyone, despite your income or profession. People with higher incomes are able to drink only bottled spring water and eat only organic food by paying higher prices, but they breathe the same air as everyone else.

At a meeting on Monday, many representatives have expressed their concerns about the air quality, too. One talked about his experience in Beijing. “After taking a taxi from the capital airport to my hotel, which took about an hour, I washed my nose and found the inside of my nose was black. We should ask ourselves this question：Why do we want to develop? It's for living a better life. Dirty air is definitely not a better life, ” he said.

China needs to develop its economy and invest (投資) in high­tech. Every Chinese has a dream to make China stronger. But without blue sky, clean water and safe food, the achievements in the economy will become meaningless. Space technologies are not to be developed for building a base on Mars so that one day all human beings can move to the red planet because they have destroyed Earth.

What the public wants is a strong and beautiful China. The great efforts must be made to promote  ecological progress and build a beautiful China. The words have shown the central government's determination to address the environment issue.

21．The effect of smog doesn't include ________.

A．the increase of people's income  B．more people suffering diseases

C．the rising of PM2.5 readings    D．patients increasing in hospital

22．Why has smog become a common concern?

A．Because people have to pay higher prices.  B．Because a popular online­post discussed it.

C．Because we have to develop industry.      D．Because nobody can avoid it.

23．The underlined word “they” in Paragraph 6 refers to “________”．

A．space technologies       B．other planets

C．human beings           D．industrial development

24．From the last two paragraphs we can infer that ________.

A．high­tech can completely solve the problem of pollution

B．we must protect the environment while developing economy

C．we can move to Mars after the earth has been destroyed

D．we must protect the environment while developing economy