题目内容：

    Hundreds of thousands of lives were saved in 2017 alone because of the improvement of the environment, according to a new research. Fine particle pollution declined rapidly following the new rules on industrial emissions and the promotion of clean fuels, according to the study, published on Monday in the National Academy of Sciences of the United States of America. The study, which focused on the period from 2013-2017, was conducted by a group of Chinese researchers and scientist.

PM2.5, as this kind of pollution is known, is so small that it can enter the bloodstream, potentially leading to cancer, stroke and heart attack in the long term. After rapid industrialization and weak regulations left the country with a reputation for smog and bad air quality, Chinese authorities started to take air pollution seriously in 2008.

In 2013, Beijing had PM2.5 concentrations 40 times higher than levels recommended by the World Health Organization(WHO), and the government introduced its toughest-ever clean air policies that year. The study found “significant declines” in PM2.5 levels across China from 2013-2017, with new emissions rules for vehicles. The authors say this “confirms the effectiveness of China’s recent clean air actions.”

These recent actions have seen Beijing fall out of the top 100 most-polluted cities in Asia in recent years, with the pollution levels 10% lower across Chinese cities between 2017 and 2018, according to a report by Greenpeace and Air Visual. Shanghai, the country’s largest city and financial capital, has also made environmental advances, such as adopting strict recycling regulations. Public pressure has been the driving force of pollution policy in China.

Air pollution is a global issue, and India is now home to 22 of the 30 most polluted world cities, according to the Greenpeace and Air Visual report. In the US, a recent study said air pollution was linked to more than 107,000 deaths in 2011 and cost the country $866 billion.

1.What saved many lives in China?

A.China’s clean air policies.

B.The increased particle pollution.

C.The study by researchers.

D.The reduction of the clean fuels.

2.Why did PM2.5 cause many diseases?

A.It was called smog.

B.It made the air cleaner.

C.It went into the blood.

D.It had a bad reputation.

3.When did Chinese government decide to treat the pollution?

A.In 2008. B.In 2013.

C.In 2017. D.In 2018.

4.What did people in Shanghai do to protect the environment?

A.They built the thermal power plants.

B.They stopped using industrial boilers.

C.They made Shanghai financial capital.

D.They tried to recycle some rubbish.