Simple tenses in English

The table below shows the comparison of simple teneses in English.

Past Simple	Present Simple	Future Simple
She wrote an email yesterday.	She writes an email every day.	She will write an email tomorrow.
The activity happened at a specific moment in the past.	The activity happens (is repeated) at present time.	The activity will happen in the future. The future tense is described or suggested.
expressions: last week, a month ago, in 2009, yesterday	expressions: once a week, often, sometimes, from time to time, usually, always	expressions: tomorrow, in the next two months, before she is twenty, next week, the day after tomorrow