1 Charles Darwin wasn't an American. He was an Englishman.
2 William Shakespeare didn't write 'Don Quixote'. He wrote 'Hamlet'.
3 My great-grandparents weren't bankers. They were teachers and office workers.
4 We didn't have mobile phones in the 1970s. We had them in the late 1990s (в конце 90-х).
5 My father didn't study at Oxford. He studied at Saint Petersburg State University.
6 My brother didn't study Chinese at school. He studied English.
7 I didn't take ten exams in winter. I took four exams.
8 I didn't fail (at) my last examination. I never failed an examination.
9 I didn't do my homework yesterday morning. I did my homework yesterday evening.
10 I didn't see the President of our country yesterday and I didn't speak to him. I saw the mayor of our city.