Page 859 - Wordsmith A Guide to College Writing

Active Voice and Passive Voice

2 Identify and use active and passive voice

or correct unnecessary shifts in voice.

Look at this sentence:

At the clothing store, Eric tried on several jackets, but none were

purchased.

It contains an unnecessary shift from active voice to passive voice.
Here is the corrected version:

At the clothing store, Eric tried on several jackets, but he

purchased none.

Active voice means that the subject of a verb performs the action
described by the verb, as in the following sentence:

Tom ate the hamburger.