Computers must be of great use to ________ doing the scientific research.

题目

Computers must be of great use to ________ doing the scientific research.
　A．those　　　　　　　 B．who 　C．those who 　　　　　D．whomever
为什么呢?

答案

因为 those doing == those people who are doing --------强调‘正在’做某事的人们.