阅读理解
Humans were designed to stand upright(直立). And yet in this modern world, too many of us spend our days with our heads lowered for a simple reason: we're staring at the tiny screen of a smart phone.
People spend an average of 2 to 4 hours each day with their neck bent while shooting off emails or texts. That's 700 to 1,400 hours a year. The success of social media has led to a rapid development of bad smart phone posture.
The average adult head weighs 10 to 12 pounds when it's in the upright position. However, because of the gravity, bending your head at a mere 15 degree puts 27 pounds of pressure on your spine(脊椎)；a 30 degree neck bend could equal(等于) 40 pounds of pressure; a 45 degree bend adds the force of 49 pounds, according to the research from Dr. Kenneth Hansraj from New York. These stresses may lead to many problems.
It's no secret that correct posture is better for your back. According to the researchers, good posture is described as ears aligned(成一条直线) with the shoulders. In proper alignment, spinal stress disappeared. It is the best position for the spine. Standing tall doesn't just make you look better; it improves your health, too. Other studies have found good posture has even been connected to ways of behaving. People who have poorer posture often have poorer physical and emotional health.
The researchers describe bad posture（姿势）as “the head in a forward position and the shoulders dropping forward in a rounded position”. Bad posture has been connected to many medical problems, including headaches and other problems, depression and heart disease. This is why Hansraj said it's important to be mindful of your smart phone posture. While it is nearly impossible to avoid the technologies that cause these problems, people should make an effort to look at their phones with a correct posture.
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在抛物线上，且
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