Tenses indicate the time of an action in relation to the time of the speaking or writing about that action.

The most common problem with tenses—shifting confusingly from one tense to another—is discussed in section S4. Other problems with tenses are detailed in this section, after the following survey of tenses.

Survey of tenses

Tenses are classified as present, past, and future, with simple, perfect, and progressive forms for each.

simple tenses The simple tenses indicate relatively simple time relations. The simple present tense is used primarily for actions occurring at the same time they are being discussed or for actions occurring regularly. The simple past tense is used for actions completed in the past. The simple future tense is used for actions that will occur in the future. In the following table, the simple tenses are given for the regular verb walk, the irregular verb ride, and the highly irregular verb be.

perfect tenses More complex time relations are indicated by the perfect tenses. A verb in one of the perfect tenses (a form of have plus the past participle) expresses an action that was or will be completed at the time of another action.

progressive forms The simple and perfect tenses have progressive forms that describe actions in progress. A progressive verb consists of a form of be followed by a present participle. The progressive forms are not normally used with certain verbs, such as believe, know, hear, and seem.

Special uses of the present tense

Use the present tense when expressing general truths, when writing about literature, and when quoting, summarizing, or paraphrasing an author’s views.

General truths or scientific principles should appear in the present tense unless such principles have been disproved.

Because Galileo’s teaching has not been discredited, the verb should be in the present tense. The following sentence, however, is acceptable: Ptolemy taught that the sun revolved around the earth.

When writing about a work of literature, you may be tempted to use the past tense. The convention in the humanities, however, is to describe fictional events in the present tense.

When you are quoting, summarizing, or paraphrasing the author of a nonliterary work, use present-tense verbs such as writes, reports, asserts, and so on to introduce the source. This convention is usually followed even when the author is dead (unless a date or the context specifies the time of writing).

In MLA style, signal phrases are written in the present tense, not the past tense. (See also MLA-3b.)

apa note: When you are documenting a paper with the APA (American Psychological Association) style of in-text citations, use past tense verbs such as reported or demonstrated or present perfect verbs such as has reported or has demonstrated to introduce the source. (See APA-3b.)

The past perfect tense

The past perfect tense consists of a past participle preceded by had (had worked, had gone). This tense is used for an action already completed by the time of another past action or for an action already completed at some specific past time.

Writers sometimes use the simple past tense when they should use the past perfect.

The past perfect tense is needed because the action of leaving was already completed at a specific past time (when dinner was served).

Some writers tend to overuse the past perfect tense. Do not use the past perfect if two past actions occurred at the same time.

Sequence of tenses with infinitives and participles

An infinitive is the base form of a verb preceded by to. (See B3-b.) Use the present infinitive to show action at the same time as or later than the action of the verb in the sentence.

The action expressed in the infinitive (to pay) occurred later than the action of the sentence’s verb (had hoped).

Use the perfect form of an infinitive (to have followed by the past participle) for an action occurring earlier than that of the verb in the sentence.

The liking occurs in the present; the joining would have occurred in the past.

Like the tense of an infinitive, the tense of a participle is governed by the tense of the sentence’s verb. Use the present participle (ending in -ing) for an action occurring at the same time as that of the sentence’s verb.

Use the past participle (such as given or helped) or the present perfect participle (having plus the past participle) for an action occurring before that of the verb.