There are 12 main verb tenses in English and each serves a distinct purpose. This is a general overview on how the different tenses are used in writing.
Used for completed past actions. Regular verbs take the “–ed” stem.
I studied yesterday.
Used for actions that happen for extended period of time in the past or when one past action interrupts another. It is formed using was/were + ing form of another verb.
I was studying when the phone rang.
Used to indicate an event preceded another past event. This tense is formed using had + third form of a verb.
I had studied Business models before enrolling in the Commerce program at SMU.
Past Perfect Continuous
Used for an event that took place over an extended period of time in the past and then stopped in the past.
I had been studying Business models for two hours. when you arrived.
Used for schedules, routines, and habits. It is formed with the first form of the verb. Note that most third person present simple verbs take an ‘s’
Eric reviews his lecture notes daily.
Used for actions that are happen in this exact moment. It is formed using am/is/are + -ing form of another verb. If there is a time indicator, it can sometimes be used for the future.
I am creating this handout. (right now)
I am reviewing this handout tomorrow. (future as it has the time indicator tomorrow)
Eric is reviewing his lecture notes in the Atrium.
Used for actions that happened at an unspecific time before the present and to talk about experiences. The time must be unspecific for this tense to be used.
Eric has reviewed his lecture notes.
Present Perfect Continuous
Used for something that started in the past but continued until the present. It is formed using have been + ing form of the verb.
I have been working here for three years.
Eric has been reviewing her lecture notes for 3 days.
Has two forms will and going to that have specific uses. There are some exceptions to these rules:
Will is used for promises and voluntary actions
Going to is used for plans
Sarah will be an engineer.
Used when an action takes places in the future but it is interrupted. It is formed using will be + -ing form or going to + -ing form of a verb.
Jake will be studying sociology tonight before Shannon gets there.
Sarah will be working as an engineer next summer.
Indicates an action that will be completed by a particular time in the future. It usually contains a time indicator. It is formed using will + have + past participle
She will have completed her degree by May 2015.
Sarah will have worked as an engineer for 4 years.
Future Perfect Continuous/Progressive
Used to describe an event that will take place and end at a particular moment in the future. It is formed using will have been + ing form or going to + have been + ing form of the verb.
Jane will have been working as a tutor for four years by 2016.
Sarah will have been working for 4 years by 2019.