Used to talk about how long an action will have been in progress at a certain time in the future.

Used to make predictions and talk about plans.

Used to talk about an action that will be in progress at a certain time in the future.

Used to talk about an action that had been going on for some time in the past, until another action took place.

Used to talk about a past action which took place before another past action, which serves as a reference point.

Used to talk about an action that started some point in the past and continued up to the moment of speaking, or moments before.

Used to talk about an action that is in progress at the moment of speaking. Also used to talk about a future action whenever arrangements have already been made.

Used to talk about an action that was in progress at a certain moment in the past.

Used to talk about the completion of an action in the future.

Used to state a fact or talk about a present state.

Used to talk about past actions which are concluded.

In general, used to talk about past actions which have some kind of impact or reflection in the present. Also used to talk about a past action which happened at an undetermined time, and with words such as ever, never, already, yet, since.