1.The man is very rich. We met him in Thinh Duc market yesterday.
=> The man whom we met in Thinh Duc market yesterday is very rich.
2. People will build a stadium in Thinh Duc commuse next time. We will be used it in the future.
=> People will build a stadium which we will be used in the future in Thinh Duc commuse next time
3. The building is the oldest in our city. It was built over 100 years old=> ago.
=> The building which was built over 100 years ago (ago đúng hơn nha) is the oldest in our city