Cooper is a private-security detective, one of many (who) patrol one prosperous enclaves like ~.

I know the students, some of (whom) are clever.

~ from his clients, many of (whom) had lost their entire savings.

He tells the same story to (whoever) will listen.

문장 모두 뒤에 동사가 오는데 왜 2,3번째문장에서만 whom이 쓰이나요?? 너무 헷갈립니다..