Past Tenses

Past Simple:

use: past completed actions from a definite time in the past. (last year, in 1974, on Monday, this weekend, etc)

form: - ed, irregular verbs list, auxiliary did or didn´t
eg: Yesterday, I separeted two bags full of garbage but I didn´t recycle everything.

Present Perfect:

use: action from an indefenite time in the past, still happening in the present or related to the present( never, ever, yet, just, already, recently, always, till, now, since, etc...)

form: Have/has(auxiliary) + Past Participle of the verbs
eg: The gradual destruction of the planet has begun.

Present Perfect Continuous

use: long action that has finished a little time ago or will continue into the present.

form: Has been/Have been (auxiliary) + Present participle of the verbs (-ing form)
eg: Poaching on deforestation have been causing biodiversity loss.

Past perfect

use: action that happened before another action in the past. (after/before)

form: had(auxiliary) + Past Participle of the verbs
eg: The environmentalist arrived after the loggers had cut the trees.

Past perfect continuous

use: long action that happened before another action in the past.

form: had been(auxiliary) + Present participle of the verbs ( - ing form)
eg: I noticed the tiger had been struggling in the trap for a long time.

Past Continuous

use: longer action that happens simuktaneously with ( or interrupted by ) another action in the past.

form: was/were(auxiliary) + present participle of the verb ( -ing form)
eg: When I saw him, he was dumping, glass into the glass container.