Formas Presentes: everyday, on Fridays, at the moment, now, as well as adverbs of frequency such as always, usually, sometimes (for present habits and routines). Days of the weeks followed by 's' such as Mondays, Tuesdays, etc.
He sometimes finishes work early.
Marjorie is listening to the radio at the moment.
Peter goes jogging on Saturdays.
Formas Pasadas: when I was ..., last week, day, year, etc., yesterday, ago (two weeks ago, three years ago, four months ago, etc.)
He visited his friends last week.
I didn't see you two days ago.
Jane flew to Boston yesterday.
Formas Futuras: next week, year, etc., tomorrow, by (the end of the week, Thursday, next year, etc.) in X time (in two weeks time, in four months time, etc.)
I'm going to attend a conference next week.
It won't snow tomorrow.
They're going to visit New York in two weeks.
Formas Perfectas: since, yet, already, just, for
Michael has worked here since 1998.
Have you finished reading the paper yet?
He's just gone to the bank.
Pruebe su conocimiento con esta breve prueba.