1. Who: Who is coming to the party tonight? (Refers to people)
2. Whom: The person whom I met yesterday is a famous author. (Refers to people, object of a verb or preposition)
3. Whose: The woman whose dog ran away is very upset. (Indicates possession)
4. Which: The book which I am reading is very interesting. (Refers to things)
5. That: The car that I bought is very reliable. (Refers to both people and things, can be used instead of who, whom, or which in some cases)
6. Where: This is the house where I grew up. (Refers to a place)
7. When: Can you tell me the time when the meeting starts? (Refers to a time)
8. Why: Do you know the reason why she left? (Refers to a reason)
9. What: I don't understand what you're talking about. (Refers to something unknown or unspecified)
10. Whoever: Whoever wins the race will receive a trophy. (Refers to any person)