The English tense-aspect system has two morphologically distinct tenses; present and past. The word tense refers to the time period in which the verb of a sentence places an action. For the grammatical tense, there are subcategories called aspects. Aspect refers to the duration of an event within a particular tense. In other words, the aspects: Simple, progressive, perfect, and perfect progressive.
No marker of a future tense exists on the verb in English; the futurity of an event may be expressed through the use of the auxiliary verbs "will" and "shall", by a present form plus an adverb, as in "tomorrow we go to New York City", or by some other means. Past is distinguished from present–future, in contrast, with internal modifications of the verb. These two tenses may be modified further for progressive aspect (also called continuous aspect), for the perfect, or for both. These two aspectual forms are also referred to as BE +ING[8] and HAVE +EN,[9] respectively, which avoids what may be unfamiliar terminology.
Aspects of the present tense:
- Present simple (not progressive, not perfect): "I eat"
- Present progressive (progressive, not perfect): "I am eating"
- Present perfect (not progressive, perfect): "I have eaten"
- Present perfect progressive (progressive, perfect): "I have been eating"
(While many elementary discussions of English grammar classify the present perfect as a past tense, it relates the action to the present time. One cannot say of someone now deceased that he "has eaten" or "has been eating". The present auxiliary implies that he is in some way present (alive), even if the action denoted is completed (perfect) or partially completed (progressive perfect).)
Aspects of the past tense:
- Past simple (not progressive, not perfect): "I ate"
- Past progressive (progressive, not perfect): "I was eating"
- Past perfect (not progressive, perfect): "I had eaten"
- Past perfect progressive (progressive, perfect): "I had been eating"
Aspects of the future:
The modals will and shall and their subjunctive forms would and should are used to combine future or hypothetical reference with aspectual meaning:
- Simple future, simple conditional: "I will eat", "I would eat"
- Future progressive, conditional progressive: "I will be eating", "I would be eating"
- Future perfect, conditional perfect: "I will have eaten", "I would have eaten"
- Future perfect progressive, conditional perfect progressive: "I will have been eating", "I would have been eating."
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No marker of a future tense exists on the verb in English; the futurity of an event may be expressed through the use of the auxiliary verbs "will" and "shall", by a present form plus an adverb, as in "tomorrow we go to New York City", or by some other means. Past is distinguished from present–future, in contrast, with internal modifications of the verb. These two tenses may be modified further for progressive aspect (also called continuous aspect), for the perfect, or for both. These two aspectual forms are also referred to as BE +ING[8] and HAVE +EN,[9] respectively, which avoids what may be unfamiliar terminology.