2 . When we see well, we do not think about our eyes very often. It is only when we cannot see perfectly that we realize how important our eyes are.

People who are near-sighted can only see things that are very close to their eyes. Everything else seems blurry(=unclear). Many people who do a lot of work, such as writing, reading and sewing become near—sighted.

People who are far-sighted suffer from just the opposite problem. They can see things that are far away, but they have difficulty in reading a book unless they hold it at arm’s length. If they want to do much reading ,they must get glasses, too.

Other people do not see clearly because their eyes are not exactly the right shape. They have what is called astigmatism (散光). This, too, can be corrected by glasses. Some people’s eyes become cloudy because of cataracts (白内障). Long ago these people often became blind. Now, however, it is possible to operate on the cataracts and remove them.

Having two good eyes is important for judging distances. Each eye sees things from a slightly different angle. To prove this to yourself, look at an object our of one eye; then look at the same object out of your other eye. You will find the object’s relation to the background and other things around it has changed. The difference between these two different eye views helps us to judge how far away an object is. People who have only one eye cannot judge distance as people with two eyes.

1. We should take good care of our eyes ________.

A．only when we can see well

B．only when we cannot see perfectly

C．even if we can see well

D．only when we realize how important our eyes are

2. When things far away seem indistinct(模糊不清) , one is probably ________.

A．near-sighted	B．far-sighted
C．astigmatic	D．suffering from cataracts

3. Having two eyes instead of one is particularly useful for ________.

A．seeing at night	B．seeing objects far away
C．looking over a wide area	D．judging distances

4. People who suffer from astigmatism have ________.

A．one eye bigger than the other

B．eyes that are not exactly the right shape

C．a difficulty that can be corrected by an operation

D．an eye difficulty that cannot be corrected by glasses

3 . Protecting your eyesight is one of the most important things you can do to help maintain your quality of life.     1     Consider these simple guidelines:

Protect your eyes from harmful UV(紫外线的) light. When you stay outdoors during daytime, always wear sunglasses that protect your eyes from 100 percent of the sun’s harmful UV rays.     2    

Look for warning signs of changes in your vision.     3    Some trouble signs to look for are double vision, hazy (模糊的) vision and having difficulty seeing in low light conditions. Other signs and symptoms of potentially serious eye problems that require immediate attention include red eyes, frequent flashes of light, eye pain and swelling.

    4     A comprehensive eye exam, including enlarging your pupils (瞳孔), can determine your risk for major eye diseases that have no early warning signs or symptoms. An eye exam also can make sure that your prescription for eyeglasses or contact lenses (隐形眼镜) is up to date.

    5     But keeping a healthy lifestyle and having regular eye exams will certainly decrease your risk of developing a sight-stealing eye problem that otherwise might have prevented.

A．This may help reduce your risk of cataracts(白内障) and other problems.

B．Test your eyesight for free in an online eye exam.

C．In a word, eye care is very important, no matter how old a person is.

D．With a little careful and loving care, you can keep your eyes healthy as you age.

E．Get your eyes checked at least every two years.

F．It’s true that following these steps is no guarantee of perfect vision through your lifetime.

G．If you start noticing changes in your vision, see your eye doctor immediately.

4 . 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(阻力), 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, drawn-out increases in blood pressure can cause long-term health problems. 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.

1. What can we learn about crossing one's legs?

A．It is a very bad social habit.

B．It is usually practiced on purpose.

C．It can do harm to people's health.

D．It can make others feel uncomfortable.

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

3. In the third paragraph "pins and needles" probably means______.

A．slight sharp pains

B．being a little nervous

C．serious muscle injuries

D．being highly flexible

4. What is the main purpose of the text?

A．To compare common habits.

B．To give readers some advice.

C．To evaluate effects of an experiment.

D．To introduce research methods.