21. He told me to hold the ladder because it was rather unsteady

22. The teacher asked us to read the question twice and not to write in the margin

23. His wife told him not to do any thing dangerous 

24. Mr.Green said that I had better not leave my money lying about

Mr.Green advised me not to leave my money lying about

25. Thanh advised Minh to tell the truth

26. She asked Jim to turn off the light

27. Mary said that she would like to speak to Susan but she was bathing her babies

28. Thu asked Huong what kind of books she read

29. Mr.Smith asked Mary how she went to school

30. Ba asked Tam how often she washed her clothes

Giải thích: Sử dụng linh hoạt các kiến thức về câu gián tiếp

- S1 + asked + (objective) + WH (when, where, why, which, how) + S2 + V (lùi thì)

- S + asked/told/advised/ordered/wanted/warned + sb + (not) + to V-inf