It helps to know when and how to use active or passive constructions. Which choice is clearest or most appropriate for your purpose, audience, and type of writing?
Active
Example:
The committee will investigate the high failure rates in these courses.
Explanation:
- The committee = subject is the AGENT who performs the action
- will investigate = ACTION (verb requiring an object)
- the high failure rates in these courses. = GOAL (object)
Passive
Examples:
The high failure rates in these courses will be investigated.
or
The high failure rates in these courses will be investigated by the committee.
Explanation:
- The high failure rates in these courses = (subject is the GOAL)
- will be investigated = ACTION
- OPTIONAL – [by the committee] = AGENT can be omitted
Sometimes the GOAL (the object of the verb) is more important than the AGENT (subject). The passive allows us to place the goal/object at the front of the sentence and, if appropriate, to omit the agent altogether.
Examples:
1. We need more doughnuts for the meeting.
Explanation:
- We = SUBJECT (agent) performing/responsible for action
- need = Transitive verb (present tense)
- more doughnuts for the meeting. = OBJECT of verb (what?)
2. More doughnuts are needed for the meeting.
Explanation:
- More doughnuts = OBJECT (goal) performing action or being acted upon.
- are needed =
- Auxiliary “TO BE” conveys tense
- Past participle verb
- for the meeting. = AGENT is optional; can be omitted
CAUTION: Much institutional writing uses what is called a “passive-nominalized” construction, like this one—
“An investigation will be conducted into the high failure rates in these courses.”
To nominalize means turning a verb into a noun. This is a useful trait in English, but overusing nominalizations results in lack of clarity. Combining nominalizations with unwanted uses of passive voice often creates a writing style known as “bureaucratese.” The effect of this style can be chillingly remote as well as unclear.
From the Writing Center at the University of North Carolina at Chapel Hill:
"A passive construction occurs when you make the object of an action into the subject of a sentence. That is, whoever or whatever is performing the action is not the grammatical subject of the sentence. Take a look at this passive rephrasing of a familiar joke:
Why was the road crossed by the chicken?"
For more, check out their 2.47 mins video on the passive voice: https://www.youtube.com/watch?v=NOKFFbC-4Ic