to talk about an event that took place in a definite time the past

to talk about an event that took place in a indefinite time the past

to refer to an action that is already finished in the past

to refer to an action that happened in the past but still affects the present

to refer to an action that started in the past but took some time to take place

talk about a present action

Talk about an action that someone has already done before

Talk about an action someone still hasn't done

Talk about an action that has recently finished

Create sentences associated with time phrases like:

since, for, yet, still never, ever, already, just, always, until, so far,...

to talk about an action taking place now

to give emphasis on the lenght of time of an action which started in the past and is still going on

to talk about an action that took some time in tha past

to talk about an action that lasted for an indefinite period of time in the past and its effects are still evident

to emphasise an action that has been taking place for quite some time

has...finished

has...finishing

have ...finishing

have...finished

has... finish

haven't going

haven't gone

haven't went

hasn't gone

haven't going

has been studying

has studied

have studied

have been studying

has...trying

have...tried

has ... tried

have ... try

has ...trying

Have...be...work

has...been...worked

has...being ...working

has...been...working

have...been...working

have ...visit

has ...visited

have...visiting

have...visited

has ...visiting