Great inventions change the way we live ,The first great invention was one that is still very important today—the wheel. This made  36  easy for men to carry heavy things and to travel long distances, for  37 （century）after that,there were few inventions that had as much effect as the wheel.Then in the early 1800’s, the world started to change  38   （great）. In the second half of the 19th century, many great inventions  39  （make）.  Among them were the camera, the electric light and the radio, all of  40  have become a big part of our life today. The first part of the 20th century saw many great inventions,  41  （include）the helicopter, movies with sound and the computer. It was also  42  time when a new world was made. Men began looking for ways to go into space. Russia and the US made the first step,  43  （follow）by Europe and Japan. China has also made great contributions to  44    （explore）outer space these years, but we still have a long way to go. New inventions are being made all the time. Who  45  （know）what the world will be like in the future?