Утвердительная форма:
-в ед.числе: was+ing
например;
-I was writing
-He was doing
Отрицательная форма:
-в ед. числе:was not +ing
например:
-I was not writing
-He was not going
Вопросительная форма:
-в ед.числе: was+подлежащее+ing
например:
-Was i writing?
-Was he doing?