Every year these chips get cleverer, but their size gets smaller, and their cost gets less. They are used in watches, calculators and intelligent machines that we can use in many ways.
In the future we will not need to work with tools in the old way. Machines will do everything for us. They will even talk and play games with us. People will have plenty of spare time. But what will they do with it?
Human beings used stone chips for more than two million years, but human life changed very little in that time. We have used silicon chips for only a few years, but life is changing faster every day. What will life be like twenty years from now? What will the world be like two million years from now?
20. The stone chip is thought to be the most important tool because it ______.
A. was one of the first tools
B. developed human capabilities
C. led to the invention of machines
D. was crucial to the development of mankind