Chuyển các câu sau sang câu bị động. 1, Mary is cutting a cake with a sharp knife ......................................................................... 2.They have provided the victims with food and clothing ................................................................................................. 3. The children looked at the woman with a red hat ...................................................................................... 4. People speak English in almost every corner of the world. .............................................................................................. 5, You musn't use this machine after 5:30 p.m .................................................................... 6. After class, one of the students always erases the chalk board ...................................................................