When writing sentences with lists or series, use parallel construction, which means putting the elements of the list or series in a grammatically equal form. Look at the following examples of parallel construction to get an idea of what this means; the elements in grammatically equal form are in bold.
Parallel construction is also handy when using colons followed by numbered, itemized or bulleted lists. In labs, resumes and other documents, make sure that items following a colon are in parallel construction.
- the reason for the experiment
- what will it demonstrate?
- how the exhibit will be set up
- what materials will be used?
- the reason for the experiment
- the proof of the experiment
- the construction of the demonstration
- the materials for the experiment
Elements that are being added to or are being compared or contrasted by the use of pairs of conjunctions, like both...and, either...or or not only...but, can be expressed more clearly and emphatically by the use of parallel construction.
In this sentence, the reader expects ‘demonstrates’ to be ‘demonstrated’ because the first verb of that sentence, ‘gave’, is in the past tense. The verb tense, or time, of the sentence has shifted in a confusing way. There is no logical reason for it.
A shift in verb tense indicates a shift in time. Sometimes more than one verb tense is used in a sentence, paragraph or essay when the meaning calls for such a shift. The shifts in tense may be necessary to explain changes or continuities over time or for other reasons.
- to describe action in works of literature or other art forms such as film, opera, television shows etc.
- to explain the ideas, arguments, and interpretations of writers, scholars, historians, scientists etc
- to describe general truths
In a sentence in which a verb has an active voice, the subject of the verb is acting. In a sentence in which a verb has a passive voice, the subject of the verb is being acted upon or is passive. The passive voice makes meaning unnecessarily indirect or unclear. Writing instructors and professors usually advise students to use the active voice.
Active voice generally follows this form: subject- verb - object
The passive voice, on the other hand, allows the actor or doer in a sentence to remain invisible. The actor or doer does not even have to appear.
Passive voice generally follows this form: object - is/was/were - past-tense verb - subject (not always present)
Rules and models destroy genius and art.
The school board cancelled the outdoor education program.
Genius and art are destroyed by rules and models.
The outdoor education program was cancelled.
Passive Voice and the Missing Subject
An error was made.
People were killed.
These passive sentences don't tell us who made the error or who killed the people. Active sentences would.
Passive Voice and Identified Subject
Even when the actor is present in a passive sentence, he, she or it seems not particularly responsible for the action because they are distanced from it by being positioned after the verb.
An error was made by two Canadian pilots.
People were killed by the bombs.
Notice how changing these passive sentences into active sentences makes them both more direct and less wordy.
Two Canadian pilots made an error.
The bombs killed people.
Reasons for Choosing the Passive Voice
Use the passive voice when the actor is unknown or irrelevant.
It may be that in a time of widening uncertainty and chronic stress, the historian's voice is the most needed. -- Barbara Tuchmann
Although this sentence doesn't tell us who needs the historian's voice, we assume that all people, humanity at large, have this need. Because we are able to make this assumption, the passive voice is useful here.
Use the passive voice when you want to focus on the action or the thing being acted upon, not the doer.
After a thorough evaluation, the outdoor education program was cancelled.