3. Ann had fed the cats before she went to the cinema.

=> The cats had been fed (by Ann) before she went to the cinema.

4.The students have discussed the pollution problems since last week.

=> The pollution problems have been discussed (by the students) since last week.

6.Some people will interview the new president on TV.

=> The new president will be interviewed on TV (by some people).

9.He has broken his nose in a football match.

=> His nose has been broken in a football match(by him).