a) My friend was talking on the phone when I came into the room.
Мой друг разговаривал по телефону, когда я вошёл в комнату.
was talking — Past Continuous
b) What were you doing at 4 o'clock yesterday afternoon?
Что ты делал вчера днём в 4 часа?
were doing — Past Continuous
c) I was speaking English when my teacher came into the classroom.
Я разговаривал на английском, когда мой учитель вошёл в классную комнату.
was speaking — Past Continuous
d) Omar was reading a book when Colin phoned him.
Омар читал книгу, когда Колин ему позвонил.
was reading — Past Continuous
e) Dmitry was writing a letter when I walked into the room.
Дмитрий писал письмо, когда я вошёл в комнату.
was writing — Past Continuous