2. He didn't remember (who/whom he had seen the night before.) (" Whom" is the object of " had seen.")
3. Many people (who/whom have started here went on to start their own business.) (" Who" is the subject of " have started.")
4. They gave the award to (whoever/whomever had the most points at the end.) (" Whoever" is the subject of " had." Even though it comes after a preposition, the object of the preposition is the whole clause, not " whomever." One word cannot be both an object and a subject, and we need a subject to go with every verb.)
5. The organization is open to (whoever/whomever can afford to pay the dues). (" Whoever" is the subject of " can afford.")
6. She was the one (who/whom he said was the best worker.) (" Who" is the subject of " was." Don't let the &quo the said" in between the subject and verb throw you off.)
7. He is the man (who/whom some people say is responsible for all of this.)(" Who" is the subject of " is.")
8. They are going to put the blame on (whoever/whomever is the most vulnerable.) (" Whoever" is the subject of " is." See numbers 4 and 5.)
9. Do you want to know (who/whom I think will win?) (" Who" is the subject of " will win." See numbers 6 and 7.)
10. (Whoever/whomever comes in first) will win the prize. (" Whoever" is the subject of " comes.")
11. The police identified the suspect (who/whom they had arrested.) (" Whom" is the object of " had arrested." The subject is " they.")
12. This is the man (who/whom we must see first.) (" Whom" is the object of " must see.")