Прошедшее время группы "continuous" используется для
обозначения действия, имеющего отношение к определённому
моменту в прошлом или для описания обстановки.
Прошедшее время группы "continuous" образуется при
"to be" = "was/ were" + "ing" :
What were you doing at five yesterday? = Что вы
делали в пять часов вчера?
They were having dinner when I came = Когда я вошёл,
I was waiting for you at five o'clock yesterday = Я
ждал вас в 10 часов вчера.
What were you doing when I came in? = Что вы
делали, когда я вошёл?
I was writing to my sister at seven o'clock in the
morning = В семь часов вечера я писал письмо сестре.
My son was doing his lessons when his friend came to
see him = Мой сын готовил уроки, когда пришёл его
We went out. There were a lot of people in the street. Some
of them were hurrying home from work. A boy was
walking on the other side of the street. Some other
children were playing near their house. An old woman
was walking to the park with a little girl. I went to
the park, too, and sat down at a bench.