Active Voice vs. Passive Voice
In order to understand the concept of Active and Passive voice, we need to remember the order of words in an English sentence.
Typically, the order is Subject – Verb – Object.
Julia is helping Sam.
In this sentence, “Julia” is the subject. The subject is the entity in the sentence that executes the action of the verb, which, in this sentence is “help” (is helping). The object, “Sam”, is the entity that is receiving the action of the verb. “Julia is helping Sam” is an example for an active sentence.
In a passive voice sentence, the object “Sam” becomes the subject of the sentence. The previous subject, “Julia” is becoming the “agent”. In the passive voice, the verb conjugation of the verb changes. The above sentence in the active voice changes to: Sam is being helped by Julia.
To form the passive voice, use the following chart:
we use the preposition “by” in the passive voice only if we know the “agent”, or if we want to emphasize either the “agent” or a specific subject. If we do not know the “agent”, or if it is not important to know who the agent is, we do not use “by”.
These potatoes have been grown in Idaho. (It does not matter by who specifically.)
The show was cancelled. (It does not matter who exactly cancelled the show)
The show has been cancelled by the network. (We use “by” if it is important to know that it was the network who cancelled the show, or if someone asks: “Who cancelled the show?” / “By whom?)
These potatoes have been grown in Idaho by my uncle Sam, who is a farmer. (We use “by” if we want to add important information pertinent to the subject.)
The Passive Voice with Modal Verbs