下面的句子我知道:

The weather of Beijing is colder than that of Wuhan.

有人认为这里的 that 只能替代不可数名词；但也有人认为 that 可用于替代可数名词和不可数名词。我的疑问是：that 可以用于替代可数名词吗？谢谢！

解答如下：

以上属于“指示代词代替前面不可数名词用法”that可以代词不可数名词，也可以代替单数可数名词。that =the one（可数名词）

(1)that也可替代不可数名词，但是 the one则不能。

The resistance of a thicker wire is less than that of a thin one．

备注：以上例中的that都不能换成the one。

(2)that用作替代词和它所替代的名词词组的中心词的“数”可以不一致。替代单数名词时，只替代“the ＋单数名词”，不可替代“a＋单数名词”。

The song by Schubert is more tuneful than that by Britain．

（备注that＝the song。song为可数名词。）

(3)that作替代词，只能指物，不能指人。those作替代词，既可指物，也可指人。

The blonde girl I saw was older than the one you were dancing with．

备注：该句中的the one不能换成that。

The houses of the rich are generally larger than those of the poor．

    that 可以用来代替“the + 前述名词”，以避免重复。前述名词可以是可数名词，也可以是不可数名词，但后者一定要有修饰语。例如：The study of idiom is as important as that (= the study) of grammar.学习习语和学习语法一样重要。/ His life was that of a great revolutionary fighter.他的一生是一个伟大战士的一生。（摘自《薄冰英语惯用法词典》）