Passage Five
The computer is a wonderful machine. It is the most important invention since the type of engine used in cars. Today it has the greatest effect on science, industry and business, but it is being used more in education and medicine. By the end of this century it will touch the lives of everyone, even people in distant villages. It is a revolutionary invention.
The oldest kind of computer is the abacus, used in China since the sixth century. In the seventeenth century an adding machine was invented, but the first large, modern computer was built in 1973. A few years later a computer could do 5,000 additions per second. Now the computations are so fast that they are measured in nanoseconds.
Today most computers are stored-program computers, that is, they have a memory. They are getting smaller and smaller, and computing faster and faster. Even in a large computer, the part that does the actual computing is about the size of the end of a fi
A. seconds
B. microseconds
C. milliseconds
D. nanoseconds
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