three fourths of the homework have finished 怎么理解 用have finished对吗

题目

three fourths of the homework have finished 怎么理解 用have finished对吗
我在一个语法练习上找到的原题have finished 我不能理解 怎么把homework理解为复数？

答案

这句话的意思是：有四分之三的作业已经被完成了.但是have finished的说法是不对的.have finished是主动地形式,可以说 I have finished three fourths of the homework作业是被完成的,应该用被动式,应该说：have been...