A、Windows. B、A specialized software. C、MS-DOS. D、Not mentioned. C题目询问哪一个是IBM几乎所有个人电脑的标准操作系统。关键是听到“MS-DOS成为了 IBM几乎所有个人电脑的标准操作系统”，

Gates was born and brought up in Seattle. [29]At the age of 14, he founded a computer programming company with three friends and they had earned $20,000 by selling their traffic-counting system to local governments. In 1975,  he dropped out of his law course at Harvard to found the Microsoft Software Company in Washington. Gates" domination of the emerging computer industry began in 1980-1981, when he devised an operating system and licensed it to IBM. [30]MS-DOS became the standard operating system for nearly all IBM personal computers. During the 1980s, Microsoft also developed more specialized software. When the company went public in 1986,[31]Gates became a multimillionaire at the age of 31. Five years later, he was ranked as the world’s richest man. In the 1990s, Gates made a fresh fortune from sales of Windows, a system that enables a computer to be operated with on-screen symbols rather than complex keyboard commands. A revised version was launched amid huge publicity in 1995.