1 . There have been many studies that show being in nature is good for your health. Walking in the woods is good for your well-being. Living near trees can help you live longer. But when you go for a walk in the woods, what is it particularly about being in nature or being outdoors that makes you feel good? Is it the sights or smells or sounds? A new study finds it might have something to do with the birds you hear while you have a walk.

Researchers from California Polytechnic State University analyzed how much the natural sounds people hear when they’re outdoors influence well-being. They found that the “chorus (合唱)” of birds singing increased well-being in protected natural areas.

For the study, researchers placed 10 hidden, evenly spaced speakers(扬声器) on two parts of trails(小路) in the Boulder Open Space and Mountain Parks in Colorado. They played recorded songs from 11 kinds of birds. The researchers take turns to play the birdsong for a few hours a day for a week, and then turned off the speakers for a week at a time. They interviewed hikers after they passed through the areas with the speakers.

“The main result is that hikers that heard the birdsong responded to questions that showed a higher level of well-being compared to those that did not hear the birdsong,” Biology Professor Clinton Francis, who led the research, says.

Hikers who heard more birdsong on the first part of the trail said they felt better. Those who heard more birdsong on the second part reported that they thought more birds lived along that part of the trail. This feeling of more birds helps make the hikers feel better. “With the chorus, we were able to show that natural sounds have a clear effect on the quality of hikers’ experiences,” says Francis.

1. What’s the function of the questions in paragraph 1?

A．To bring in the topic of the text.	B．To advise people to walk in nature.
C．To call on people to care about nature.	D．To raise doubt about the research done before.

2. Why were the speakers placed along the trails?

A．To broadcast chorus live.	B．To remind hikers of their health.
C．To improve people’s well-being.	D．To play sounds of different birds.

3. What was the final step of the research?

A．Recording.

B．Comparing.

C．Photographing.

D．Interviewing.

4. What is the best title for the text?

A．Being in nature is good for people’s heath.

B．Walking in forests help people live longer.

C．Hearing birdsongs is good for people’s health.

D．Raising birds improves people’s living quality.