The coloursystems（系统）used by scientists and artists are completely different. An artist will mix blue and yellow paint to get a shade of green; a scientist will mix green and red light to create yellow. The printed page in a magazine is yet another system.
Scientists recognize the lightprimaries(原色) are red, green and blue. When mixed, red and green light rays produce yellow, blue and green produce cyan, red and blue produce magenta. Red, green and blue mix to create white (light). This colour model is used in computer monitors, television sets and theater.
Most artists recognize red, yellow and blue as the three basic primary colours. These primaries are the pure colours which can not be created by mixing any other colours.
In the print industry, cyan, magenta, yellow and black are used as the primary colours. When you mix all the colours, the result is gray.
__________ on the colour systems.

A．Scientists and artists have the same idea

B．Scientists agree with artists

C．Scientists and artists have different ideas

D．Some of their ideas are the same

How many colour systems are mentioned in the passage?

A．Two.	B．Three.
C．Only one.	D．Four.

hich of the following isNOTtrue?

A．Red, green and blue are used in television sets.

B．If scientists want to get white, they will mix red, yellow and blue together.

C．Most artists think red, yellow and blue are the pure colours.

D．In the print industry, if you mix all the colors, you will get gray.