The agent complement is a complement of the predicate that is present only in passive voice sentences . Its objective is to establish who exercises the action of the verb with respect to the subject . It can be made up of a single word or a group of words. In this article we will provide you the information about the Agent complement in English grammar.

Passive voice and the agent complement

Passive voice sentences have the particularity that the subject is not the one who performs the action, but rather the one who receives it. For its part, the agent complement is in charge of carrying out the action of the verb . It is correlated with the grammatical subject in the active sentence.

In the passive voice, the interest is focused on the person or object that experiences the action and not on the person who performs it (agent complement). This means that the most important thing will be the subject of the sentence, and all the attention is directed to it. But this does not mean that the agent does not exist, otherwise it is there even if it does not expressly appear .

Example:

• The cars were repaired by the best mechanics .

In this passive sentence, we find that the agent complement (the best mechanics) is the one who performs the action (were repaired) that affects or receives the subject (The cars). However, the emphasis is mainly on the subject (The cars), rather than the agent complement (the best mechanics). The phrase seeks to give more importance to “cars” than to “the best mechanics.”

Passive sentences with agent complement

Most passive voice phrases in English do not explicitly include the agent complement. However, agent complements always exist in passive sentences , whether they appear clearly or not.

If it is necessary to express it with a specific phrase, then it must be preceded by the preposition “by” . There are three specific circumstances in which complement agents always appear in the sentence, these are:

When it is a proper name of an artist, inventor, discoverer or innovator :

• The Yellow House was painted by Vincent Willem van Gogh .
• Insuline were discovered by Oscar Minkowski and Josef von Mering .

If it is a phrase with an undefined name that offers important information :

• All that research investigation was done by a brilliant woman .
• The downtown building was destroyed by a radical terrorist .

When referring to an unexpected inanimate noun:

• Fifteen people were injured by a tornado in Florida .
• All the controls of the plane are controlled by a computerized system. 

Passive sentences without agent complement

As we already mentioned, in many passive sentences the agent is not mentioned . It may be because it is not important or it is so obvious that it is not necessary to mention it. We leave you some examples below:

• All visa applications must be sent to the embassy before October the 1st.
• The information was filled and the results have just been sent.
• We walked to work. The bus‘s being fixed.  [someone does]).

It is very common to use impersonal expressions with “it” or “there” when the agent is not important , as you can see in the following examples:

• It has been estimated that one in two children in Germany studies and speaks English.
• There were no good comments given about the speed of the new players.

It may happen that we do not know the object or the person responsible for the action in the sentence. In this case, it is common to see “someone” or “somebody” used in the active phrase. But in the passive sentence we proceed to leave these words out and simply omit the agent explicitly .

Example:

• Active voice: Someone stole my care.
• Passive voice: My car was stolen [by someone]).

How to recognize agent complements in passive sentences?

To recognize the agent complements in passive sentences, we can resort to the question , who performs the action on the subject? In this way we will quickly identify the agent.

For example:

• The cakes were eaten by our brother . / Who ate the cakes? / My brother.
• Richard is known to everyone . / Who knows Richard? / Everyone.
• The money was delivered to me by the bank teller . / Who delivered the money? / the bank teller.

The agent can also be identified by exchanging it with the subject , that is, by changing the passive sentence to a phrase in the active voice.

Example:

• The machinery was replaced by the engineer
• The shoes were repaired by our grandfather
• Messi is known to everyone = Everyone knows Messi.
• The money was sent to me by Andrew .

Other examples of passive voice sentences with Agent Complement

• On our way home, we stopped by the CIA agents .
• The new shopping mall will be opened by the owner .
• The photo was taken by my sister .
• A policeman has been attacked by terrorists .
• We were woken by the clock alarm .
• The telephone was invented by Graham Bell .