Упражнение 11. Определите, какое из предложений находится в активном, а какое

1. The lock was broken sometime after four oclock(Past Simple Passive)
Someone broke the lock after 4 o'clock.
2. Joseph Priestley discovered oxygen in 1774. (Past Simple Active)
Oxygen was discovered by Joseph Priestley in 1774.
3. The postal clerk sent the unsigned letter before I could retrieve it from the mailroom. ( Past Simple Active)
The unsigned letter was sent by the postal clerk before it could be retrieved by me from the mailroom.
4. Public speaking is taught by Professor Higgins. (Present Simple Passive)
Professor Higgins teaches public speaking.
5. Volunteer work was done by the students for extra credit in sociology.(Past Simple Passive)
The students did volunteer work for extra credit in sociology.
6. The students did volunteer work for extra credit in statistics.( Past Simple Active)
Volunteer work was done by the students for extra credit in statistics.