Chuyển từ câu chủ động -> bị động
1.Who helped her?
-->By whom ................................?
2.Who bake this cake?
-->By whom ............................?
3.Who has written this sentence on the wall?
-->By whom ...............................?
Chuyển từ câu chủ động -> bị động
1.Who helped her?
-->By whom was she helped?
2.Who baked this cake?
-->By whom was this cake baked?
3.Who has written this sentence on the wall?
-->By whom has this sentence on the wall been?