Computers can injure you. Most other injuries happen suddenly. For example, if you fall off a bike and break your arms, it happens very quickly. But computer injuries slowly.
You probably know how to ride a bike safely. Now learn to use a computer safely.
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 on (反射) the screen. If the window 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 at the same height as the keyboard. 3) Stop something 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 the 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 all be in front of your eyes. Your forearms, wrists, hands and the upper part of your legs should all be parallel (平行) to the floor. If you are sitting for a long time, get up every 30 minutes and exercise your arms, legs and necks.
Enjoy your computer, but use it safely.
【小题1】A computer screen may injure your eyes if __________.
A. you sit 60 centimeters away
B. you remember to look away
C your eyes are too close to it
D the window is on your left or your right
【小题2】Hand and wrist injuries are caused when you _________.

The moon is the 5 planet to the earth. It is smaller than the earth. Plants can’t grow on the moon because there’s 6 air or water on it.

The moon hasn’t its own light. It shines 7 the light of the sun. When the sun is shining on the 8 of the moon that faces us, it looks like a great round ball. Sometimes we can’t see the moon 9 the sun is shining on the side that faces away 10 us.

1. A. Who    B. That　　 C. If　　   D. Whether　　　　　　　　

2. A. gone    B. goes　　 C. are sent  D. are going　　　　　　   

3. A. visiting  B. look at   C. live on   D. study on　　　　　　　　

4. A. studied  B. learn　　 C. say　　 D. told　　　　　　　　　　

5. A. near    B. nearer    C. nearest  D. inside　　　　　　　　   

6. A. no　　 B. few　　  C. a few    D. a little　　　　　　   　　

7. A. to　　  B. at　　   C. back　　 D. for　　　　　　　　　　

8. A. side    B. sides　　 C. back　　 D. front　　　　　　　　  

9. A. so that   B. because  C. so　　   D. why　　　　　　　　  

10. A. through  B. to　　   C. into　　 D. from