两者都可替代“the+单数名词(可数或不可数)”，均表特指，但it指前面提到的“同一”事物，而that是指前面提到的“同类”事物。如：

　?、賂he Parkers bought a new house but ________will need a lot of work before they can move in.

　　A. they B. it C. one D. which

　　解析：答案选B。it替代 “the + house”，指的就是前面提到的the Parkers所买的那座新房子。

　?、贔ew pleasures can equal ________ of a cool drink on a hot day.

　　A. some B. any C. that D. those

　　解析：答案选C。that替代the pleasure，指与前面提到的同属“快乐的事”。

　　2. 替代词one的用法

　　one用以替代“a+单数可数名词”，表示泛指。特指的the one相当于that;the one复数形式the ones，在口语中也常用those代替;当后面有of短语时，一般用that或those，当有前置修饰语时，只能用one(s)，如the red one。one(s), the one(s), those, that都是替代“同类”事物，其中只有that可替代不可数名词。如：

　?、賅e needed a new cupboard for the kitchen. So Peter made ________ from some wood we had.

　　A. it B. one C. himself D. another

　　解析：答案选B，one替代a cupboard。

　　②Mr Zhang gave the textbooks to all the pupils except ________who had already taken them.

　　A. the ones B. ones C. some D. the others

　　解析：答案选A，后面的定语从句是特指，the ones替代 the pupils。此处也可用those。