When you think of all the ways your body can get hurt---falling off a bike, stepping on a nail, being bitten by a crazed dog---the aches and pains that come from sitting at a computer may not seem like much.
But more doctors are getting worried about just that. If you sit at a PC the wrong way, the nerves and muscles in your back, neck and arms can get out of line.
Ergonomics is the study of how people work and how jobs and equipment can be designed so that people are safer and more comfortable in the things they do---whether that’s working on a factory assembly line or sitting in front of a computer.
The monitor
You should not have to tilt（倾斜） your neck up or down to lock at the screen. Your eyes should be level with the top of the screen.
How far away should you sit? Reach your arm out so your fingertips just touch the screen.
The keyboard
It should be directly in front of you. Don’t unfold the legs on the bottom of the keyboard so that it tilts up toward you---it should be as flat as possible, or even tilted away from you. You want your wrists “neutral,” which means straight, not bent. This puts less strain on your nerves and muscles.
Arms should be close to the body. Don’t look at your fingers as you type. Use a document holder to hold papers at the same level as the monitor. Keep the mouse on the same level as the keyboard and close by--- so you don’t have to reach for it.
The chair
Your feet shouldn’t dangle---the blood will pool in your feet. They should rest flat on the floor, or on phone books, if necessary. Your back needs support. Roll up a towel and stick it there.
The Body
If you think of your body as a collection of right angles when you sit at a computer, you should be just fine.
Your hips should be at a 90-degree angle to your back. That takes the pressure off the spine. And your knees should bend at a 90 degree angle so your feet are flat.
The passage mainly talks about        .

A．avoiding pains caused by using PC	B．the science of ergonomics
C．illness caused by a computer	D．how to keep fit

The underlined word “ergonomics” most probably means ______ in Chinese.  

A．管理学

B．人机工程学

C．机械工程学

D．经济学

How high should a monitor be placed according to the passage?

A．As high as your arms.

B．A little higher than your eyes.

C．A little lower than your eyes.

D．At the same level as your eyes.

How shouldn’t a keyboard be placed?

A．Tilting away from you.	B．Tilting up toward you.
C．Flat.	D．Not mentioned.

How should you place your foot?

A．Rest them on a phone book.	B．Rest them on the floor.
C．They should rest flat.	D．They should dangle.