it指代在上文提到的同一个,复数为 they
one指代在上文提到的同一类中的任何一个,特指为 the one 或者that one ,复数分别为 ones
that 指代上文提到的同类事物,单数或不可数均可,复数为those
改错练习：I have bought a call-phone,I am going to give one to my brother .
I have bought a call-phone,and I am going to give it to my brother .
The population of China is about 10 times large than of Japan.