In the sentence The dog chased the cat, the verb (chased) is active. If you turn it around, and say The cat was chased by the dog, the verb (was chased) is passive. You form the passive by using the verb be and the past participle of the main verb. For example, the passive of attack is be attacked, the passive of pay is be paid, and the passive of see is be seen. You can only use the passive with transitive verbs.
WHEN TO USE AN ACTIVE VERB
You use an active verb when you want to say that the subject of a sentence does something. For example:
She opened the window.
WHEN TO USE A PASSIVE VERB
You use a passive verb when you want to say that something happens to the subject of the sentence.
President Kennedy was killed in 1963.
You often use a passive verb when talking about the history of something. For example:
The bridge was built in the 19th century.
The company was established in 1826.
In these cases, it is much more natural to use the passive than to find a vague, active way of expressing the sentence (such as Someone built this bridge in the 19th century.).
You often use a passive verb when you are writing about science, or when you are saying how things are made. For example:
Hydrogen and oxygen can be easily mixed in this way.
Paper is made from wood.
If you used an active verb here, you would have to say who does the action â€“
information which is not known or not important.
If you want to say who does the action of the verb in a passive sentence, use by and then say who does it.
President Kennedy was killed by Lee Harvey Oswald in 1963.
The bridge was designed by Brunel.
HOW TO CHANGE AN ACTIVE SENTENCE INTO A PASSIVE ONE
There are three things you need to do in order to change an active sentence into a passive one.
1. Move the subject of the active verb to the end of the sentence, and put by in front of it.
2. Move the object of the active verb to the front of the sentence, so that it becomes the passive subject.
3. Change the verb from active to passive. You do this by adding a form of the auxiliary verb be and the past participle of the main verb.
Subject verb object
The dog chased the cat.
Subject verb by….
The cat was chased by the dog
THE PASSIVE WITH GET
You can also make a passive using get instead of be. This kind of passive is very common in conversation. Do not use it in formal writing. You often use this kind of passive to say that something happened suddenly to someone.
I got sacked by my firm. OR I was sacked by my firm.
He got hit by a car. OR He was hit by a car.
You can also use the passive with get when you want to suggest that an action is more forceful or more important to you.
I get paid on Thursday. OR I am paid on Thursday.
We often get asked this question. OR We are often asked this question