Bill Gates(11) on October 28,1955． He grew up in Seattle ,Washington．He was a very(12 ) boy．His favorite subjects at school were science and maths．( 13) he was 13 years old ,Bill started to play with computers． At that time ,computers (14) very large machines．Once he was very interested (15) a very old computer． He and some of his friends (16).lots of time doing unusual things with it． In the end ,they worked out a software program(软件程序：) with the old machine． Bill (17) it for $ 4,200 when he was only 17．In 1973,Bill (18) Harvard University．in his third year ,he left Harvard to work for a company(公司) called Microsoft． Bill began his company in 1975 (19 ) his friend Paul Allen． They thought the computer would come into every office and every home soon． So they began developing the software for personal computers． They improved(改进) the software to (20) it easier for people to use computer,．( )11．