Every English Sentence must have a Verb. A verb is basically an action. The time this action takes place is decided by the Tenses. There are three main verb tenses: Present, Past, and Future. Each main tense is divided into simple, continuous, perfect, and perfect continuous tenses.

Present finish
Past finished
Future will finish
am/is/are finishing
was/were finishing
will be finishing
have/has finished
had finished
will have finished
Perfect Continous
have/has been finishing
had been finishing
will have been finishing

Things to remember about simple tense:-
a. Present tense is the original verb form.
b. Past tense has two kinds – regular and irregular
c. Future tense needs will + verb in first form.

Examples of Regular Verbs :

1st Form (Simple Present) 2nd Form (Simple Past) 3rd Form (Past Participle)
Work Worked Worked
Talk Talked Talked
Act Acted Acted

Examples of Irregular Verbs:

1st Form (Simple Present) 2nd Form (Simple Past) 3rd Form (Past Participle)
Speak Spoke Spoken
Write Wrote Written
Run Ran Run
Sentences with irregular verbs:
run :-
I run a marathon twice a year. (present)
I ran a marathon last year. (past)
I will run a marathon next year. (future)
eat :-
I eat lunch in my office.
I ate lunch an hour ago.
I will eat lunch in one hour.