Sure! Here are the correct relative pronouns filled in:

1. There are eighteen different kinds of penguins **that** live south of the equator.
2. Thank you very much for the present **that** you sent me.
3. This is Mrs. Jones, **whose** son won the championship last year.
4. His girlfriend, **who** trusted absolutely, turned out to be an enemy spy.
5. The bus crashed into a queue of people, four of **whom** were killed.
6. A man bought in a little girl, **who** was cut by flying glass.
7. Mary, **who** briefly didn’t turn up, ended by having lunch with Peter.
8. He paid me $5 for cleaning two windows, most of **which** hadn’t been cleaned for at least a year.
9. In prison, the bread, most of **which** was moldy.
10. The chair **on which** I was sitting in suddenly collapsed.

Feel free to ask if you need further assistance!