If you want to change a passive-voice sentence to active voice, find the agent in a "by the..." phrase, or consider carefully who or what is performing the action expressed in the verb. Make that agent the subject of the sentence, and change the verb accordingly. Sometimes you will need to infer the agent from the surrounding sentences which provide context.
If you want to change an active-voice sentence to passive voice, consider carefully who or what is performing the action expressed in the verb, and then make that agent the object of a by the...phrase. Make what is acted upon the subject of the sentence, and change the verb to a form of be + past participle. Including an explicit by the... phrase is optional.
This passive voice contains a by the... phrase. Removing the by the... phrase and reworking the sentence will give it the active voice.
Image Caption:Making "most of the class" the subject of the sentence moves the action of the sentence onto the class, and shifts the sentence from passive into active voice.
The agent is not explicitly stated, but it is most likely researchers. Making the agent the subject of the sentence will allow you to use the active voice.
This sentence now uses the active voice because the agent (the researchers) are now performing the action as the sentence subject.
The CIA director and his close advisors are the agent of change in this sentence, but they are not the subject. Making the agent the subject will transform the sentence into a more concise, active voice phrase.
This sentence now uses the active voice because the agent (the CIA director and his close advisors) is performing the action as the sentence subject.
The agent is not specified in this sentence.
This sentence now uses the active voice because the agent (we) is the subject of the sentence.
This active voice sentence's agent is the presiding officer, which is the subject.
Changing the sentence subject from the agent (the presiding officer) to the object of the verb (the committee's recommendation) and adding a by the...phrase transforms the sentence into the passive voice.
This sentence includes the agent (the leaders) as the subject performing the action of the verb.
This sentence now uses the passive voice because the subject has been changed from the agent (the leaders) to the object of the verb (a fair resolution).
The scientists are the agent performing the verb's action in this active voice sentence.
This passive voice sentence no longer specifies the agent (scientists) and now uses the passive voice because the verb's object (traces of ice) is now the subject.