There have been many great inventions ____  (1)  ____ change the way we live. The first great ____  (2)  ____ was the one that is still very important today—the wheel. This made it easy for man ____  (3)  ____ heavy things and to travel long distances. For ____  (4)  ____ years after that, there were ____  (5)  ____ inventions that had as much effect as the wheel. Then in the early 1800s the world started to change ____  (6)  ____. There was little unknown land left in the world. People did not have to explore much any more. They began to work instead to make life better. In the second half of the 19th century many great inventions were made. ____  (7)  ____ them were the camera, the electric light bulb and the radio. These have all become a big part of our life today.

   The first part of ____  (8)  ____ century saw more great inventions—the helicopter in 1909, movies ____  (9)  ____ sound in 1926, the computer in 1928, and jet planes in 1930. This was also a time when a new ____  (10)  ____ 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 ____  (11)  ____ ways to go into space. Russia made the first step. Then the United States took ____  (12)  ____. Since then other countries, including China and Japan, ____  (13)  ____ their steps into space. In 1969 man took his biggest step away from the earth. ____  (14)  ____ first walked on the moon. This was certainly just a beginning. New inventions will someday allow us ____  (15)  ____ things we have never yet dreamed of.