`48. `Their friends have been met at the railway station by a group of students.
- Câu bị động thì HTHT
- S + have/has + been + VpII + (by + O)
`49.` Tom wasn't allowed to take these books home by them.
- Câu bị động thì QKD
- S + was/were (+not) + VpII + (by + O)
`50. `Exercises won't be corrected by the teacher tomorrow.
- Câu bị động thì TLD
- S + will (+ not) + be + VpII (by + O)