i will talk to those students the homework of whom hasn;t been done.

但是定语从句的主语不是whom,而是the homework of whom ,就是说,其实是the homework.
祝学习好!为什么呢，就是，你把of的表示单数复数说下，或者举些粒子，谢谢诶He is one of the boys the hair of whom is quite long.Do you know the word the first 3 letters of whomare written in bold.其实我举的例子可能用whose + 名词结构更合适，但为了向你解释一下，所以都把它们变成n. +of + whom了。后面的单复数由of 前面的词决定，而不是先行词。如果不明白欢迎继续追问。