two thirds of the land are covered by water 这句话有何错误

two thirds of the land are covered by water 这句话有何错误

分数(百分数)+of+名词”结构作主语时,谓语动词的数与其中名词的数保持一致
此句中two thirds of 三分之二,做主语,
谓语动词的单复数由land决定～land 当然用is了

应将are改为is,因为land不可数名词。