Viết lại câu sao cho nghĩa không đổi

 viêt lai câu
1  no one knows why this happened ( change into passive form )
2 fire, however, wasn't the only cause of destruction ( there )
=> in addition 
3 the san francisco ferry building is the place that commuters catch their ferries ( at )
=> computers can
4 tropical forests are known to be essential to the balance of nature ( awareness )
=> we
5 i disagree that teacher discipline students physically if they misbehave ( approval )
=> i