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the one, one, it, that是经常考查的代词，the one用来替代同类事物中特指的一个。one用来替代上文提到的同类名词中的一个，表泛指，相当于“a(n)＋名词”，复数用ones。it指上文提到的同一类事物。that用来替换上文出现的带定冠词的名词，复数用those。