Computers call injure(伤害)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 happen 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(厘米)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

    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)You’re 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 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 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 neck．

    Enjoy your computer，but use it safely．

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 fight

2．Hand and wrist injuries are caused when you         ．

    A．get plenty of exercise                   B．move in the same way again and again

    C．rest your wrists on something              D．keep your elbows as high as the keyboard

3．Your eyes and hands will be safe if        ．

    A．you work near a window                     B．you often take rests from working

    C．you use a keyboard for a long time       D．the window is behind you

4．What would be the best title for the text          ．

    A．How to protect your eyes                    B．How to protect your hands and wrists

    C．How to use a computer safely              D．How to protect your back

How often does one hear children wishing they were grown ups, and the old wishing they were young again? Each are has its pleasure and its pains，and the happiest person is the one who enjoys what each age gives him without washing any time in useless regrets （悔恨）．

Childhood is a time when there are few duties to make life hard．If a child has good parents，he is fed，looked after，and loved whatever he may do．It’s impossible for him to be given so much again in his life without having to do anything in return．Also，life is always giving new things to the child．A child finds pleasure in playing in the rain, or in the snow．His first visit to the seaside makes him wild．But a child has his pains  he is not free to do things as he wishes．He is always being told not to do this，not to do that，or being punished （惩罚） for what he has done wrong．So his life is not quite happy．

When the young man starts to make his own living he becomes，free from the discipline （约束） of schools and parents．But at the same time he is made to accept duties．He can no longer expect others to pay for his food，his clothes and his room，but has to work if he wants to live comfortably．If he spends most of his time pitying about in the way that he used to as a child，he will go hungry．And if he breaks the law of the society as he used to break the laws of his parents，he may go m prison （监狱）．If，however，he works hard，keeps out of trouble，and in good health，he can have the great happiness of seeing himself do better in his job and building up his own place in the society．Old age has always been thought of as the worst age to be in，but it is not necessary for the old to be unhappy．Old age should come with wisdom and the ability to help others．They can have the joy of seeing their children doing better in life; they can watch their grandchildren growing up around them and，perhaps，best of all，they can，if their life has been a useful one，feel the happiness of having come through the fight of life safely and of having reached a time when they can lie back and rest，leaving others to go on with the fight．

1．According to the passage，to a child，______．

A．he is free of duties，but he is short of freedom

B．everything may give him pleasure，but he can't do anything as he wishes to

C．life is always new to him，but he can't do anything

D．he is always loved and has no worries，but he can't be happy

2．The writer mainly tells us that______

A．everyone lives a happy life                          B. each age has its pleasure and its pains

C．children are the happiest                     D．time is everything

3．A young man who starts to make his own living_______

A．can spend his time playing about in the way he used to as a child

B．can wait for others to feed him

C．is free to break the law of society

D．is happy to see himself getting on well with his job

4．In the writer's opinion，the old _______．

A．are useless people                        B．have to help others

C．have their own pleasure                    D．are the best group

5．Which period of one's life is the best according to the writer?

A．Childhood．                             B．Youth．

C．Old age．                               D．He doesn't tell us．