Sentences can be active or passive. Therefore, tenses also have "active forms" and "passive forms." You must learn to recognize the difference to successfully speak English.
In active sentences, the thing doing the action is the subject of the sentence and the thing receiving the action is the object. Most sentences are active.
Basic form: [Thing doing action] + [verb] + [thing receiving action]
Examples: - The professor teaches the students
- Jonh washes the dishes.
In passive sentences, the thing receiving the action is the subject of the sentence and the thing doing the action is optionally included near the end of the sentence. You can use the passive form if you think that the thing receiving the action is more important or should be emphasized. You can also use the passive form if you do not know who is doing the action or if you do not want to mention who is doing the action.
[Thing receiving action] + [be] + [past participle of verb] + [by] + [thing doing action]
| |Active |Passive | |Simple Present |Once a week, Tom cleans the house. |Once a week, the house is cleaned by Tom. | |Present Continuous |Right now, Sarah is writing the letter. |Right now, the letter is being written by Sarah. | |Simple Past |Sam repaired the car. |The car was repaired by Sam. | |Past Continuous |The salesman was helping the customer when the thief came into the...