Sure! Here’s a rephrased version of those sentences:

9. **The traffic was so congested that we couldn't return home before 8 PM.**
- It was that bad.

10. **They will open the flower garden to the public for ten days.**
- The flower garden...

11. **When he was younger, he swam every morning. He no longer does this.**
- He used to.

12. **If it doesn’t rain, there will be enough water.**
- Unless...

13. **“What subject do you enjoy most at the university, Nga?” the interviewer inquired.**
- The interviewer asked...

14. **“What are your plans after finishing school?” she asked me.**
- She asked...

15. **“Is there a good art department at your school?” he asked me.**
- He inquired...

16. **Traveling abroad for vacation is quite fascinating.**
- It is...

17. **Did Alexander Graham Bell create the telephone?**
- Did he...?

18. **They have sold that old house located at the end of the road.**
- That...

19. **Harry's residence is still in Spain, isn’t it?**
- Harry still lives...