1. He didn't work at a factory.
2. We didn't finish our homework.
3. They didn't congratulate us on our success.
Построение отрицательного предложения в Past Simple:
I, you, we, they, he, she, it + did not (didn't) + V
He worked at a factory.
He didn't work at a factory.
We finished our homework.
We didn't finish our homework.
They congratulated us on our success.
They didn't congratulate us on our success.
