A、The development of balloons. B、The weather balloons. C、The history of human being flying. D、Balloons for recreation. D本文介绍了spo

Balloons have been used for sport for about 100 years. There are two kinds of sport balloons: gas, and hot air. Hot air balloons are safer than gas balloons, which may catch fire. Hot air balloons are preferred by most balloonists in the United States because’ of their safety. They are also cheaper, and easier to manage than gas balloons. Despite the ease of operating a balloon,  pilots must watch the weather carefully.  Sport balloon flights are best early in the morning or lute in the afternoon, when the wind is light. Over the years, balloonists have tried unsuccessfully to cross the Atlantic Ocean. It wasn’t until 1978 that three American balloonists succeeded. It took them just six days to make their trip from their homes in the United States to Paris, France. Their voyage captured the imagination of the whole world.