There have been many great __1__. The first great invention was one that is still very important today——the wheel. This made it easier to carry __2__ things to travel long distances.
A In the early 1800s the world __3__ to change. There was little unknown lleft in the world. People did not have to explore much any more. They began to work instead to make life better.
B In the second half of the 19th century many great inventions were made. Among them were the camera， the electric light the radio. These all became a big part __4__ our life today.
C The first part of the 20th century saw more great inventions： the helicopter in 1909， movies with sound in 1926， the computer in 1928， jet planes in 1930. This was also a time __5__ a new material was first made. Nylon came out in 1935. It changed the kind of clothes people wore.
D The middle part of the 20th century brought new ways to help people __6__ disease. They worked very well. They made people healthier let them live __7__ lives. By the 1960's most people could expect to live to be at least 60.
EBy this time most people had a very good life. Of course new inventions continued to be made. Man began __8__ ways to go into space. Russia made the first step. Then the United States took a step. Since then other countries， including China Japan， have made their steps into space.
F In 1969 man took his biggest step away from earth. Americans first walked on the moon. This is certainly just a __9__ though. New inventions will someday allow us to do things we have never yet __10__.
G
H1. A. discoveries B. creations C. invention D. Inventions
