当主语是分数或百分数时,谓语动词的单复数由of后面的名词决定.
如：Surface是不可数名词,只能接单数动词is；
of后接buildings,为可数名词,后面应接复数动词.
相关介绍
1）Two thirds of the desk is painted red. the desk为可数名词单数，则动词用三单is；
2）Two thirds of the studnents in my class are boys. the students是可数名词复数，所以动词也用复数形式are；
3）One fifth of the water comes from the underground. the water为不可数名词，所以动词也用三单形式comes.
