Crossing your legs is an extremely common habit; most people don’t even notice that they’re doing it when they sit down. While you may find it comfortable to sit with one knee crossed over the other, it might be causing health problems that you are not aware of.
A study published in Blood Pressure Monitoring stated that sitting with your legs crossed can increase your blood pressure. The reason for this is that the blood in your legs has to work against gravity to be pumped back to your heart and that crossing one leg over the other increases resistance, making it even harder for the blood to circulate. This causes your body to increase your blood pressure to push the blood back to the heart. You won’t feel any immediate effects, but repeated, drawnout increases in blood pressure can cause longterm health issues. So, planning to sit for a long period of time? Don’t keep your legs crossed.
“Crossing your legs at the knee can also cause pressure on the major nerve in your leg that passes just below your knee and along the outside of your leg，” explains Richard Graves, a medical expert. This pressure can cause numbness and temporary paralysis(麻痹) of some of the muscles in your foot and leg, preventing you from being able to raise your ankle—what we know as that “pins and needles” sensation. While the feeling of discomfort may only last a minute or two, repeatedly crossing your legs until they feel numb can cause permanent nerve damage.
So next time you sit down, try to get yourself in the habit of sitting with both of your feet on the floor. Not only will it help your posture and stability, but it will also save your health in the long run.
【解题导语】 本文是一篇科普说明文。研究表明，虽然跷二郎腿是常见的习惯，但是该习惯会引起血压的升高，还会导致膝盖以下的重要神经受损。所以不要跷二郎腿，要有正确的坐姿。
1．What can we learn about crossing one’s legs?
A．It is a very bad social habit.
B．It is usually practiced deliberately.
C．It can do harm to people’s health.
D．It can make others feel uncomfortable.
C 解析：细节理解题。根据第一段的第二句可知，跷二郎腿会引起健康问题，故C项正确。
2．According to the study, sitting with your legs crossed can ．
A．affect your blood pressure
B．resist gravity effectively
C．lead to heart attacks easily
D．improve the function of legs
A 解析：细节理解题。根据第二段的第一句可知，研究表明，跷二郎腿会引起血压的升高，故A项正确。
3．In the third paragraph “pins and needles” probably means “ ”．
A．slightly sharp pains
B．being a little tired
C．serious muscle injuries
D．being highly flexible
A 解析：词义猜测题。根据第三段的“This pressure can cause numbness and temporary paralysis(麻痹) of some of the muscles in your foot and leg, preventing you from being able to raise your ankle”可知，这种压力会导致腿部和脚的一些肌肉暂时麻痹，使人无法站立，有一种针刺感；据此可以判断，画线词意为“轻微的针刺感似的疼痛”，故A项正确。
4．What is the main purpose of the text?
A．To compare common habits.
B．To give readers some advice.
C．To evaluate the effects of an experiment.
D．To introduce research methods.
B 解析：写作意图题。根据全文内容尤其是最后一段可知，本文通过分析跷二郎腿这一习惯导致的健康问题，建议人们不要跷二郎腿，要有正确的坐姿，故B项正确。
