This winter, the air quality over the north China plain was so bad that it was actually off the standard scale. The air pollution reached levels that the World Health Organization describes as dangerous. On Thursday, heavy smog blanketed most of northern and eastern China again. 
It is reasonable to ask why the air pollution is so bad this winter. Weather conditions and topographic(地形学的) factors have been given as reasons, but, although contributing factors, these are not to blame. The worsening air pollution is linked to an energy mix that relies heavily on coal and to motor vehicle emissions(排放). But despite the astonishing growth of motor vehicles in our cities, it is the burning of coal that is the biggest cause of air pollution. More than half of the country's power plants are located in the eastern region and China's coal consumption has more than doubled in the past decade, reaching 3.8 billion tons last year, accounting for almost half the world's total coal consumption. And with coal occupying nearly 70 percent of the country's primary energy consumption, it has become critical to reduce the use of coal if we are to solve the nation's overall air pollution problem.
In the face of the poisonous air recently, one citizen said, "we have nothing but hot air to purify the skies". In fact, the government plans to have 350 billion yuan ($55.67 billion) investment in improving coal-fired facilities and limiting the use of yellow-label cars that do not meet the Euro I emissions standard and so on.
However, it would be far more effective to reduce emissions at the source, which means that the biggest challenge currently facing government departments is saying "no" to the country's air polluting offenders. According to the Joint Prevention and Control Plan on Air Pollution in Key Regions released recently by the State Council, the amount of coal the nation consumes is set to rise by 30 percent during the period of the 12th Five-Year Plan. This is not going to let anyone breathe easier. 
This highlights a key problem when it comes to environmental issues in this country - economic development comes first. The fundamental cause of the worsening air pollution is the idea of economic growth at any cost, which has resulted in ever-worsening pollution. And the priority(优先权)given to economic growth presents another problem, namely the failure of existing environmental protection policies and regulations to control pollution. For instance, the current weak regulations covering emissions would suggest there has been a significant reduction in emissions when clearly this is not the case. Also those enterprises found breaking the regulations are still far lower than the cost of treating the pollution they produce. This means even if many large-scale enterprises with lagging production capacity(能力) fail to meet the requirements for environmental protection, the environmental protection department is incapable of shutting these enterprises down or forcing their relocation. 
Dealing with air pollution requires taking action at the local level to reduce vehicle emissions and at the regional level to reduce industrial emissions. But it also requires giving more priority to environmental issues in policymaking. Our hope is that the environmental protection department will be truly capable of saying "no" to pollution, and it will raise standards and effectively enforce them, and that governments at all levels will prioritize quality of life not just economic growth.
The writer mentions the heavy smog in parts of China in Paragraph1 in order to_____.

A．remind people to stay in doors because of the bad air quality

B．show people’s concern about the priority to economic growth

C．introduce the issue about the serious air pollution

D．highlight the importance of government’s policies and regulations

Why is it a big challenge for the government to say “no” to the air polluting offenders in China?

A．Because enterprises are encouraged to develop economy at the cost of the environment.

B．Because much emphasis has been laid on economic growth regardless of the cost.

C．Because it’s impossible to relocate the enterprises for lack of money.

D．Because the production capacity of enterprises falls behind the required speed.

It can be learned from the passage that the essential reason for the worsening air conditions in China is_______.

A．the sharp growth of coal consumption in recent years

B．the rapid increase of motor vehicles in cities

C．the building of power plants in northern China

D．the poor weather conditions caused by complex geographical factors

According to the writer, which of the following is the key to solving the air pollution problem?

A．Giving priority to economic development in policymaking.

B．Making environment-friendly policies and carrying them out effectively.

C．Increasing investment in the construction of coal-fired facilities.

D．Limiting the use of cars not meeting the required emission standard

Which best describes the writer’s tone in the passage?

A．Pessimistic.

B．Convincing.

C．Doubtful.

D．Concerned.