16. Long said to Hoa that he couldn't answer her difficult questions.

17. Her father told him that he didn't need to water the flowers because it rained the night before.

18. He said he was a student.

19. They said that they were learning English then.

20. Tom said that his friend was coming the following week.

21. We said that we would overcome that difficulty.

22. Nam said that he could solve that problem.

23. Dick said that he had to leave at eight.

24. He said that he had something to show me then.

25. She said she was leaving for Hue the following morning.

26. Tom said to her that he would come with her as soon as he was ready.

27. The father said to us that he had to go then.

28. Paula asked Jack if he could help her.

29. Mike asked Mary is she was free next Saturday.

=>
16. Long said to Hoa that he couldn't answer her difficult  questions.
17. Her father told him that he needn't water the flowers because it had rained the night before.
18. He said that he was a student.
19. They said they were learning English then.
20. Tom said that his friend was coming the next week.
21. We said that we should overcome that difficulty.
22. Nam said that he could solve that problem.
23. Dick said that he had to leave at eight.
24. He told me that he had something to show me then.
25. She said that she was leaving there for Hue the following day.
26. Tom said to her that he would come with her as soon as he was ready.
27. My father said to us that he had to go then.
28. Paula asked if Jack could help him.
29. Mike asked Mary if she was free the next Saturday.