simple Past Tense,Simple Present Tense and Simple Future Tense.

Simple Past Tense.
= Simple past tense refers to action which occurred at a specific time in the past,completed action and past status.
example : We went to library yesterday.
              : She finally mailed the letters.

Simple Present Tense.
= Simple present tense indicate routine action and fact.
example : We usually have a dinner at 7pm everyday.
              : Some birds fly south for the winter.

Simple Future Tense.
= We use the simple future tense to talk about things that will happen at a time later than now, discuss for future event.
example : I am going to watch movie tonight.
              : i am going to my grandmother house next week.