Verbs express a particular action (throw) or state of being (was). In addition, verbs help express who or what performs the action (person), how many people or things perform the action (number), the speaker's attitude toward or relation to the action (mood), and whether the subject is the giver or receiver of the action (voice). Perhaps the most obvious characteristic of verbs, however, is how the verb tenses express time.
Different verb forms are used in combination to express when actions occur. The simple present, past, and future tenses simply place events in time. The perfect tenses (they occur with have, has, and had) express events or actions completed; the progressive tenses (-ing verbs used together with helpers such as is, was, and were) show actions or events that are continuing.
Intentional shifting of verb tense
A statement such as the following intentionally mixes verb tenses:
I had decided to add Anthropology 11 when I discovered it already had filled up and the instructor would not be accepting any more students.
The mixed verb tenses here are intended to convey in what order things happened, what actions are completed, and what actions are continuing. The class had filled and the speaker had decided (both actions completed in the past) before he or she discovered the class was full. And the instructor is at present turning away students and will continue to turn them away for the foreseeable future.
In the following example, a statement about past actions is followed by a statement of a general truth:
I had decided to add Anthropology 11 when I discovered it already had filled up; it is unwise to wait until the last minute to add a required class.
Generalities and truisms like this (it is unwise to wait) are expressed in the simple present tense, even if they are imbedded in a statement written in a past tense.
Unintentional shifting of verb tense
Clearly, intentionally shifting verb tenses can convey a great deal of information. However, when verb tenses shift for no good reason, meaning becomes garbled. In general, avoid unnecessary changes in verb tense. This is a particular problem in personal narratives, where it is common to see something like this:
I was undecided about my major when I was a freshman. I wanted to study journalism but I like art, too. I find that sketching is relaxing and helped reduce stress, while journalism was a high-energy, often stressful class.
The verb shifts are unnecessary and make it more difficult for the reader to follow. Here is the statement revised to a consistent past tense:
I was undecided about my major when I was a freshman. I wanted to study journalism but I liked art, too. I found that sketching was relaxing and helped reduce stress, while journalism was a high-energy, often stressful class.
In personal narratives, you may choose to use either past or present tense verbs. Just do not mix them as this writer did:
He turns the key in the ignition, but only heard the relentless, useless chugging of an engine unwilling to turn over. He glanced left, then right. He cannot see the approaching train through the driving rain, but he could hear it, a low moaning wail still distant enough that he thought he still might be able to save the car.
Revised to a consistent past tense, this story is more coherent:
He turned the key in the ignition, but only heard the relentless, useless chugging of an engine unwilling to turn over. He glanced left, then right. He couldn't see the approaching train through the driving rain, but he could hear it, a low moaning wail still distant enough that he thought he still might be able to save the car.
In this case, however, you might be more successful in recreating the suspense of the moment by keeping to a consistent present tense:
He turns the key in the ignition, only to hear the relentless, useless chugging of an engine unwilling to turn over. He glances left, then right. He cannot see the approaching train through the driving rain, but he can hear it, a low moaning wail still distant enough that he thinks he still might be able to save the car.
The literary present tense
For discussing literary works, the preferred tense is the present:
Author Michael Crichton frequently addresses bioethical questions of this sort. His Jurassic Park character Ian Malcolm is a kind of devil's advocate, a doomed protagonist who asks the unasked question: "We can--but should we?"
This statement includes one about the author and his intentions or techniques, and another about a character in one of his books; both are constructed in the literary present tense. Use literary present tense for book and article reviews, summaries, and critiques.
Critiques of musical performances, art shows or other artistic works also may use the literary present tense.
For more information on verbs, see the TIP Sheet Verbs.