6. Volunteers will help the flood victims clean their village

⇒The flood victims will be helped clean their village by Volunteers 

S + will + V + O

⇒ S + will + be + VII + O

7. " Why did you come late for school yesterday?”

⇒ The teacher asked him why He had come late for school the day before

Why + do/does/did + S + V?

⇒S + asked O + Why S + V lùi thì

8 "I try to learn hard to pass the entrance exam."

My sister said that she tried to learn hard to pass the entrance exam

9. "My students are preparing the hall for their meeting." à

⇒ The teacher informed His students were preparing the hall for their meeting.

Câu 8+9

S + said/told/informed/... + (O) + V lùi thì

6. the flood victims are help cleaning their village

7. .... the reason why he came to school late

8. ..... to learn hard to pass the entrance

9. .... that students were preparing the hall for their meetings