I think three fourths_of the materials llistened to at the beginning of the exam___are_easy.

题目

I think three fourths_of the materials llistened to at the beginning of the exam___are_easy.
nearly three fourths of the earth ___is conered by sea
为什么一个用are 一个用is

答案

看of 后面词是可数名词还是不可数,如果是可数,像materials,谓语动词就要用复数.如果是不可数,像earth,就用单数.