1. Did anyone clean the windows?
=> Was the windows cleaned?
2. Did anyone invite Ann to the party? => Was Ann invited to the party?
I don't know. We should have invited her. => I don't know. She should have been invited .
3.Did anyone see you? => Was you seen?
No, but someone might have seen me if it hadn't been dark. => No, but I might have been seen if it hadn't been dark.
4.Has someone repaired this machine? => Has this machine been repaired?
Well ,it's working again so someone must have repaired it.=> Well, it's working again so it must have been repaired.
5. Did someone throw those old letters away. => Were those old letters thrown away?
Yes, but it was a mistake. We shouldn't have thrown them away.=> Yes, but it was a mistake. They shouldn't have been thrown away.
cậu tham khảo nhé!