替代词one，that，it的用法在历届高考题中出现的频率较高，是高考的热点之一。下面谈谈它们的一些具体用法：
　　1.one可指人或物，只替代可数名词，One是泛指，但有限定修饰语，如the，this，that之类修饰就变成了特指：that只指物，不指人，可替代可数名词或不可数名词，具有“特指”性质。例如：
　　One should wash one's hair regularly.There were two boys there. They chosethe strong one.那里有两个男孩，他们挑选了身体好的。
　　The new designs are much better than the old ones.这些新的图样比旧的好多了。
　　The study of idioms is as important as that of grammar.学习惯用法与学习语法同等重要。