阅读理解：
In your schoolbags, you may have a pencil, some kinds of pens, a ruler, and some books. None of these th ings grow in the fields. They were all made in factories. And, of course, they were invented by some people. There have not always been pencils o r pens, a ruler and books. Thousands of years ago no one knew about these things.
Who invented them first? How did they have such c lever ideas? We always don’t know. There have been thousands of inventions, large and small, in the human history. Some of these inventions have changed the world. Such as paper, printing, radios, telephones and computers, and we know the inventors. But we have forgotten most of the other inventors.
