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(2019·陕西检测二)Whenever I hear a recording of John Denver singing “Sunshine on My Shoulders”， I find myself smiling, drawn to a love of the sun and the outdoors I’ve had for years as a Michigan native. Walking barefoot to the lake, playing without shirts in the sunlight, and breathing fresh air feel good. As a doctor I can tell you they are also good for your heart.
Studies have found higher rates of high blood pressure among people with the lowest sun exposure. One reason may be due to nitric oxide(一氧化氮), a gas whose function is activated when your skin is exposed to the sun’s rays. It reduces both heart attack and stroke risks. Vitamin D, which sunlight helps your body produce, is also linked to better health. So walk outdoors for 15 to 30 minutes daily.
In Japan, walking through forests to keep healthy has become a popular practice. Apparently they want to enjoy the fresh air. But research on 280 volunteers found that people had a reduced heart rate, and lower blood pressure when they walked through a forest than when they spent time in an urban area.
One of the consequences of modern society is that rarely is our body in direct contact with the ground. The earth has an electrical current. Direct contact with it may be stabilizing force for good health. Although “earthing” or “grounding” is considered alternative by mainstream medicine, research shows that the practice seems to be able to reduce heart disease risks.
So, walk around barefoot wherever possible, let your backyard grass tickle your feet, and dig your toes into sandy beaches.
【解题导语】 本文是一篇议论文。作者通过叙述自己的经历、感受和一些研究发现，告诉人们户外活动有益于心脏。
1．The first paragraph is meant to ________．
A．show the author likes the song very much
B．put forward the argument of the passage
C．suggest that the author loves nature crazily
D．indicate the author is a Michigan native
B 解析：推理判断题。根据第一段的描述可知，作者写这段的目的是提出文章的论点。
2．Sunbathing’s good for heart because ________．
A．the sun’s rays make nitric oxide work
B．sunlight can help people keep warm
C．the sun’s rays can help replace vitamin D
D．vitamin D reduces blood circulation
A 解析：推理判断题。根据第二段中的“One reason may be due to nitric oxide(一氧化氮), a gas whose function is activated when your skin is exposed to the sun’s rays. It reduces both heart attack and stroke risks.”描述可推知，日光浴对心脏有好处是因为阳光能使一氧化氮工作。
3．It’s believed that walking through forests can ________．
A．make people popular
B．help breathe in fresh air
C．reduce blood pressure
D．help escape noisy cities
C 解析：细节理解题。根据第三段的“But research on 280 volunteers found that people had a reduced heart rate, and lower blood pressure when they walked through a forest than when they spent time in an urban area.”描述可知，人们普遍认为穿过森林可以降低血压。
4．The best title of the passage should be ________．
A．Nitric Oxide Has Magic Functions
B．Walking Barefoot Builds the Body
C．Sunbathing Is Good for Health
D．Outdoor Activities Benefit the Heart
D 解析：标题归纳题。根据全文内容，尤其是第一段中的“Walking barefoot...for your heart.”及最后一段可知，这篇文章的主旨是户外活动有益于心脏。
