**To indicate that these three were more prominent than any others, it should say /the three most prominent companies/. If the intention were, instead, to indicate that these companies were //merely among a number of highly prominent ones//, it should say /three of the most prominent companies/.
**This sentence aims to emphasize the special prominence of just three specific companies, as opposed to all other companies.
**//Where three most prominent companies is not preceded by a definite article//, it is unidiomatic.
前提和结论在论证有没有电脑和会不会购买的关系。实现低价的方式、换电脑的原因、竞争对手的价格、买电脑的目的都和论证无关
是滴