Subordinate clauses

Find the subordinate clauses in these sentences. 

1. Teacher Bryan makes an announcement, when it has invented some English Writing Skills (EWS), to inform the others about them. 
2. Most people will be happy if teacher Bryan teaches them an array of writing skills. 
3. The centre where Teacher Bryan taught has been visited by millions of people. 
4. Many people came to mastertuition in the 1990s hoping to learn many English Writing Skills (EWS). 
5. All the offices are closed because it is the fourth in July. 
6. Mother's Day, which is celebrated in May, has been observed since 1914. 
7. Bryan, who is a famous second language specialist, is also a writer.