Past Progressive (continuous)

progressive actions in the past.

progressive actions in the present.

-ed.

-ing.

have.

to be.

am reading

reading

was reading

will read

will play

was play

was plaing

was playing

Were | dancing

Was | dancing

Were | dance

Was | dance

Was | rides

Is | ride

Were | riding

Was | riding

to be in the present (am\is\are) + the -ing of the mais verb.

-ed.

the auxiliary did + -ing.

to be in the past (was\were) + the -ing of the main verb.

while

when

and

were dancing

was dancing

danced

They were playing when it started to rain

it started to rain when they where playing

it starts to rain when they played