Chuyển sang câu bị động 1 he had visted his mother bejore 7:pm 2 the boy had taken his dogs to the park 3 the cluldren had cleand the class at 7:pm 4 we had put the book on the table 5 he had made some cakes in the kitchen 6 we had met him at the airpot 7 my class had propared a party at the garden 8 we had organized a pary at the class 9 we had invited their friends to the party 10 the woman had planted frees in the garden