1. He is carrying out a research on how people spend their money for clothes.
→ A research on how people spend their money for clothes is being carried out by him. 
2. Although I had all the necessary qualifications, they didn’t offer me the job.
→ Despite having all the necessary qualifications, they didn’t offer me the job.
3. “Please do not litter as you are walking along the coast”, the guard said to us.
→ The guard told us not to litter as we were walking along the coast
4. I haven’t bought any clothes since my trip to Hanoi.
→ The last time I bought clothes was in my trip to Hanoi.
5. They think that a garden would be a perfect setting for the house.
→ It is thought that a garden would be a perfect setting for the house.
6. Jack’s parents made him study a lot for the entrance exam to high school.
→ Jack was made to study a lot for the entrance exam to high school by his parents
7. You can’t register for a course abroad if you don’t have a passport.
→ Unless you have a passport, you can’t register for a course abroad.
8. “Why don’t we visit the Royal Citadel first?” Quang said.
→ Quang suggested  that we visit the Royal Citadel first.
9. People expect that he will join the company soon.
→ He is expected to join the company soon.
10. Shall we use Perfume Pagoda as a theme of the presentation?
→ She suggests using Perfume Pagoda as a theme of the presentation.