A

A【解析】第一个步骤说 “First，decide on themain reasons that you want a computer．Is this con-?puter very useful for you?Is the most important rea-son to play games or to help with your business or to?help with your school work?”这是购买计算机首先应考虑的事项，而其他各项重要性均不及The?first step，所以选A项。