1 The children were writing their compositions when the teacher came.
2 While I was sitting there it began to rain so I ran home.
3 Jack's father was reading a book when he heard something outside the house.
4 When my sister and I were closing a window we saw a strange man.
5 When I went out this morning the sun was shining and the birds were singing.
Past Continuous. Прошедшее продолжительно время . определенное время в прошлом.
используется вспомогательный глагол прошедшего времени was ( в единственном числе и с местоимениями she he it) were ( со множественном числе с местоимениями they we you) основной глагол меняется к нему добавляется окончание ing.
форма этого времени. was were + Ving. ( v = verb = глагол основной)