分数作主语要根据分数所修饰的名词，如果该名词是可数名词则用复数，不可数名词则用单数。
Three quarters of the population are Chinese.
四分之三的人口是中国人。
Three quarters of it is made of water.
它的四分之三是由水组成。
About three-fourths of the surface of the earth is covered by the sea.
地球表面四分之三的部份玻海覆盖着。
分数主语单数还是复数
分数修饰名词作主语时，谓语动词由分数后面的名词决定人称和数。如果主语时单数名词或不可数名词，谓语动词用单数如果分数后面名词是可数名词复数，谓语动词用复数。
