passive and active voice

In the passive voice the action is the main subject in the sentence and the subject comes to the direct subject, so the verb acts upon the subject. Every single passive voice sentence has two verbs. 

You use the verb “to be” but you need to conjugate it and the main verb is always in past participle.

Example: Each meal is prepared with loving care by the award-winning chef.

​In the active voice, the sentence's subject performs the action. The active voice is used when you want the reader to focus on the subject of your sentence and the action it is doing.

Example: The award-winning chef prepares each meal with loving care.

The subject of the active sentence becomes the agent complement of the passive. It appears it is introduced by "by".

If you want to change an active sentence to a passive one, you must, the main verb is replaced by the auxiliary "to be" followed by the main verb in participle.

How to change from passive to active?

If you want to change a passive-voice sentence to an active voice, consider carefully who or what is performing the action expressed in the verb. Sometimes you will need to infer the agent from the surrounding sentences which provide context.