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 is 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（肘）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……平行） the floor. If you are sitting for a long time, get up every 30 minutes and exercise your arms, legs and neck.
