There have been many great inventions that change the way we live. The first great ____29____ was one that is still very important today—the wheel. This made it easy for man ____30____ heavy things and to travel long distances. For hundreds of years after that, there were ____31____ inventions that had as much effect as the wheel. Then in the early 1800’s the world started to change ____32____ . There was little unknown land left in the worlD、People did not have to explore much any more. In the second half of the 19th century many great inventions were made. ____33____ them were the camera, the electric light and the radio. These have all become a big part of our life today. The first part of the 20th century saw more great inventions. The helicopter in 1909. Movies ____34____ sound in 1926. The computer in 1928.And jet planes in 1930. This was also a time when a new ____35____ was first made. Nylon came out in 1935. It changed the kind of clothes people wear. Of course new inventions continued to be made. Man began looking ____36____ ways to go into space. Russia made the first step. Then the United States took another. Since then other countries, includingChina and Japan, ____37____ their steps into space. In 1969 man took his biggest step away from earth. ____38____ first walked on the moon. This was certainly just a beginning. New inventions will someday allow us to do things we have never yet dreamed of.