two thirds of crops谓语动词是复数。
分析:
分数做主语时
谓语动词根据分数后的名词决定单复数,可数名词用复数,不可数名词用单数。
如
1. Two thirds of crops in the field were harvested by them .
地里的三分之二的庄稼被他们收割。
2 .Two thirds of the students in his class have been to Beijing .
他班的三分之二学生去过北京。
3. Three fourths of the land is covered by water .
四分之三的陆地被水覆盖。
3. One third of the work has been finished by them .
他们完成了这项工作的三分之一。