题目内容：

    Are people happier in nature with blue skies overhead and fresh green grass underfoot? Could noisy streets, crowded with cars and people, make us unhappy?

The possible mental health problems of city living affect a lot of people. The World Health Organization estimates(估计)that 56 percent of the world's population lived in urban areas in 2019. The WHO adds that that amount will increase to 66 percent by 2050. People often move to cities for better jobs and more cultural activities. But are they putting themselves at risk? Maybe. Experts at the American Psychiatry Association say that “natural environments or green spaces” do much good to our mental health.

Many studies have shown that nature can calm us and make us feel happy. Nature, experts say, can also help us learn better. And experiencing nature helps people recover from the mental tiredness that comes from day-to-day work. On the other hand, mental health experts say some research suggests that city living might hurt our mental health. But they cannot say exactly why.

What are the specific aspects of the urban environment which causes some people to develop mental illness? Andrea Mechelli, a doctor at Kings College, London, states, “There have been studies where people were literally taken out of an urban environment into a rural (乡村的) environment and their symptoms would improve. And we also see that the greater the city is, the greater the risk is.” Mechelli say that someone who lives in a city is three times more likely to develop psychological problem than someone living in the country.

Kings College researchers, along with city planners, land and building designers and others wanted to learn more about city living and mental illness. So, they created a smartphone app called Urban Mind. They say they wanted to understand how different parts of the urban environment affect mental wellbeing(健康).

The researchers found that being outdoors, seeing trees, hearing birdsong, seeing the sky, and feeling in contact with nature were associated with higher levels of mental well-being. They also found that these seeming effects of nature were especially strong in those individuals at greater risk of mental health problems. The Urban Mind Project team says it hopes “the results will inform future urban planning and social policy aimed at improving design and health.”

1.Why is the question raised in the first paragraph?

A.To introduce the topic of the text.

B.To show the background of the text.

C.To ask the readers to learn the study.

D.To raise the readers' interest in happiness.

2.What does Mechelli find during his study?

A.People are attracted by the blue skies and green grass.

B.People are more content with their city life.

C.More and more people are interested in taking risks in cities,

D.City people are more likely to develop mental problems than country people.

3.What is expected of the Urban Mind research result?

A.More people will choose to live in the countryside.

B.It will bring more concern about people s mental health.

C.It will contribute to future urban planning and social policies.

D.People will be helped to improve their mental illness.

4.What is the main idea of the text?

A.Urban Mind measures the level of mental wellbeing.

B.City living may be harmful to people’s mental health.

C.Living in the countryside is better than in the city.

D.Different scientists hold different opinions on the effects of city living.