Для заполнения пропусков в тексте необходимо использовать форму Past Continuous (was/were + глагол с окончанием -ing) для описания действий, происходивших в определенный момент в прошлом.
His son (1) was playing the drums in the living room.
His daughter (2) was listening to jazz music on the radio.
Workers (3) were repairing the road in front of his house.
A dog (4) was barking in the garden.
I (5) was cutting the grass.
He (6) was not smiling.
Ответ: was playing, was listening, were repairing, was barking, was cutting, was not smiling