he has already visited a great number of different places in Australia.

问题描述:

he has already visited a great number of different places in Australia.
in可以换成of吗?我感觉可以,但不很确定!

在语法上是没有问题的,也就是可以的,因为a great number of 是一个固定搭配,与后面的of 无关.但在实际生活中并无这样的表达,因为略显重复.