There is no denying that students should learn something about how computers work, just as we expect them at least to understand that the internal-combustion engine (内燃机) has something to do with burning fuel, expanding gases and pistons (活塞) being driven. For people should have some basic idea of how the things that they use do what they do. Further, students might be helped by a course that considers the computer’’s impact on society. But that is not what is meant by computer literacy. For computer literacy is not a form of literacy (读写能力); it is a trade skill that should not be taught as a liberal art. Learning how to use a computer and learning how to program one are two distinct activities. A case might be made that the competent citizens of tomorrow should free themselves from their fear of computers. But this is quite different form saying that all ought to know how to program one. Leave that to people who have chosen programming as a career. While programming can be lots of fun, and while our society needs some people who are experts at it, the same is true of auto repair and violin-. Learning how to use a computer is not that difficult, and it gets easier all the time as programs become more "user-friendly". Let us assume that in the future everyone is going to have to know how to use a computer to be a competent citizen. What does the phrase "learning to use a computer" mean It sounds like "learning to drive a car", that is, it sounds as if there is some set of definite skills that, once acquired, enable one to use a computer. In fact, "learning to use a computer" is much more like "learning to play a ", but learning the rules of one may not help you play a second , whose rules may not be the same. There is no such a thing as teaching someone how to use a computer. One can only teach people to use this or that program and generally that is easily accomplished. The author’’s purpose in writing this passage is_____.