just / already / yet

Certain time in the past or just / already / yet?

Do you want to express that an action happened at a certain time in the past (even if it was just a few seconds ago) or that an action has just / already / not yet happened?

Simple Past	Present Perfect Simple
certain time in the past Example: I phoned Mary 2 minutes ago.	just / already / not yet Example: I have just phoned Mary.

Certain event in the past or how often so far?

Do you want to express when a certain action took place or whether / how often an action has happened till now?

Simple Past	Present Perfect Simple
certain event in the past Example: He went to Canada last summer.	whether / how often till now Example: Have you ever been to Canada? / I have been to Canada twice.

Emphasis on action or result?

Do you just want to express what happened in the past? Or do you want to emphasise the result (a past action's consequence in the present)?

Simple Past	Present Perfect Simple
Emphasis on action Example: I bought a new bike. (just telling what I did in the past.)	Emphasis on result Example: I have bought a new bike. (With this sentence I actually want to express that I have a new bike now.)

Signal Words

Simple Past	Present Perfect Simple
yesterday ... ago in 1990 the other day last ...	just already up to now until now / till now ever (not) yet so far lately / recently