The six tenses show differences in the time of an action or a state of being, and using different tenses changes the meaning of a sentence.

Present Tense. The present tense is used to express an action or to state a fact that is occurring at the present time. The present tense also can be formed using auxiliary verbs for emphasis or to express intention.

• • I live here.
  • I am living here. (progressive)
  • I do live here. (emphatic)
  • I can live here. (conditional)

The present tense also is used to indicate habitual action or something that is true at all times.

• • She goes out every evening.
  • My grandfather believed that silence is (instead of was) golden.

Writers occasionally use the present tense when reviewing the contents of a book or describing past events to bring them vividly to life for the reader. This form of the present tense is known as the literary or historical present.

• • In his book on Alexander the Great, the Greek historian Arrian dismisses romantic legend and concentrates on sifting truth from fiction.

Past Tense. The past tense is used to express action or to help make a statement about something that occurred in the past and has not continued into the present.

• • I lived there.
  • I was living there while I was in school. (progressive)
  • I did live there. (emphatic)

Future Tense. The future tense is used to express an action or to help make a statement about something that will occur in the future.

• • I will (shall) live there.
  • I will be living there. (progressive)
  • I am going to be living there. (progressive)
  • I can be living there. (conditional)

The distinction between will and shall is no longer observed by most people. The two verbs can be used interchangeably for the simple future tense in the first person. However, in some cases, such as when asking for permission or consent, shall is the only form used.

• • Shall we go to the movie?
  • Shall I put the box here?

To use will in these sentences would change the meaning. However, except for such special uses, will and shall are equally correct.

• • I shall call him.
  • I will call him.

Perfect Tenses. Perfect tenses describe actions or states of being that hap- pened at one time but are seen in relation to another time. For example, I gave a donation to the Girl Scouts is a simple statement about a past event and would be used to tell someone what happened in the past. I have given a donation to the Girl Scouts connects the past event to the present and can be used to imply a habitual or continuous action.

Present Perfect Tense. The present perfect tense is used to express an action or to help make a statement about something occurring at an indefinite time in the past or something that has occurred in the past and continues into the present.

• • • I have lived here for a long time.
    • I have lived here for three months. (The speaker is still living there.)
    • I have been living here for three months. (progressive)
    • I could have been living here instead of where I am now. (conditional)

Past Perfect Tense. The past perfect tense is used to express an action or to help make a statement about something completed in the past before some other past action or event.

• • • After I had lived here for three months, they raised the rent.
    • After I had been living here for three months, they raised the rent. (progressive)

Future Perfect Tense. The future perfect tense is used to express an action or to help make a statement about something that will be completed in the future before some other future action or event.

• • • By this October, I will have lived here for six months.
    • By this October, I will have been living here for six months. (progressive)