1. The woman is my mother who understands me best/my mother understanding me best.
2. The park which has a lake in is near our house/the park having a lake in is near our house.
3. The reason for which he comes here isn't explained.
4. What was the name of the boy from whom you borrowed this books.
5. I'll introduce you to the man whose support for the project is essential.
6. Did you know the actor whom you saw playing Hamlet.
7. The laboratory in which my brother works is well equipped
8. The years in which I was in the army are unforgettable.