Computers can injure you. Most other injuries happen suddenly. For example, if you fall off a bicycle and break your arm, it happens very quickly. But computer injuries happen slowly.

Your eyes

Too much light can injure your eyes, so never sit too close to a computer screen. Your eyes should be at least 50 centimeters from the screen. Remember to look away from it sometimes. This gives your eyes a rest.

When you use a computer, the window should be on your left or your right. If it is behind you, the light will reflect（反射）on the screen. If the windows are in front of you, the sun and the screen will both shine into your eyes.

Your hands and wrists（手腕）

Hand and wrist injuries can happen because the hands and wrists are moved in the same way hundreds of times. If you use a keyboard for a long time, follow these three rules：1）Rest your wrists on something. 2）Keep your elbows at the same height as the keyboard. 3）Stop sometimes and exercise your hands, wrists and fingers in a different way.

Your back

Some people sit for many hours in front of a computer. If you sit in a wrong way, you can injure your back or your neck. So you should sit with your back straight. The top part of the screen should be in front of your eyes. Your forearms（前臂）, wrists and hands should all be parallel to（与……平衡）the floor. If you are sitting for a long time, get up every 30 minutes and exercise your arms, legs and neck.

Enjoy your computer, but use it safely.

Straight or arched（弯的）, thick or thin—eyebrows（眉毛）come in many shapes and sizes. But what are eyebrows even for? They don’t keep us warm like our hair, or help us breathe like our noses. 【小题1】 Researchers believe that eyebrows help us communicate better.

Eyebrows allow us to better express feelings and understand others. For example, a quick flash（闪）of the eyebrows. 【小题2】 While pulling our eyebrows up in the middle is an expression of sympathy（同情）.

If you find it hard to understand, just draw a simple face on a piece of paper and draw a line above the eyes. 【小题3】 You will find that it is very easy to show anger, fear or surprise on a face.

【小题4】 They can also protect our eyes. Their arched shape can help to move rain or sweat（汗）around to the sides of our faces, keeping our eyes dry. Eyebrows can also help to keep dust（灰尘）and other things out of our eyes.

【小题5】 In that case, we would have had some other facial characteristics（特征）to perform the same way. That could make us look quite different.

Bad breath (口气) usually brings problems when you talk to others in life. It will make people around you feel bad and stay away from you.

What causes bad breath? If you don’t brush your teeth often, germs (细菌) will live in your mouth and between your teeth. It may make your breath smell terrible. Smoking (吸烟) and drinking can also make breath become bad. When there’s something wrong with your body, you may find that you talk with bad breath.

How can you stop bad breath? Here is some advice. It’s necessary for you to use some mouthwash (漱口水) or clean your mouth with water after meals. It can stop germs from staying in your mouth and between your teeth. Brushing your teeth at least twice a day is also a good way. You should brush your teeth for more than two minutes each time. Never stay up late at night, or you may get a sore throat and it may cause bad breath. You’d better not eat food like onions or anything with special smells before meeting others.

If you don’t want to have bad breath, make sure to have good habits in life. You’d better keep away from drinking and smoking. Looking after your teeth and mouth well can help you keep fresh breath all the time.