Perfect tenses: have done, had done, will have done

Form: I have eaten, you have eaten, he/she/it has eaten, we have eaten, they have eaten.

Use 1: Started in the past, still continuing. 'I have lived here for 10 years.'

Use 2: Past action with relevance now. 'I have lost my keys.' (Result: I cannot get into the house now.)

Use 3: Experiences in life. 'I have visited France.' (At some point in my life.)

Time markers: for, since, ever, never, just, already, yet, recently.

Form: I had eaten, you had eaten, etc. (Same for all subjects.)

Use: Something that happened BEFORE another past event.

'When I arrived at the station, the train had already left.' (Train left first. I arrived second.)

'She had finished her work before her boss came in.'

Most common with words like: before, after, by the time, when.

Form: I will have eaten, etc.

Use: Something that will be completed by a future point in time.

'By 2030, I will have retired.'

'By the end of the week, we will have finished the project.'

Always pairs with a future time marker (by + time).

Regular verbs: same as simple past (walked, worked, played).

Common irregulars: be → been, go → gone, see → seen, do → done, eat → eaten, give → given, write → written, take → taken, speak → spoken, know → known, find → found, drink → drunk, sing → sung, run → run, come → come, become → become.