1.Изберите верный вариант: He ... his car a month ago (bought

1. He bought his car a month ago. This sentence is in Past Indefinite. Ago is one of the keywords of Past Indefinite.
2. He started work when he was twelve.

When he was twelve he started work.

1. Did Ann paint this picture two years ago? (General question).

When did Ann paint this picture? (Special question).

Ann painted this picture two years ago, did not she? (Disjunctive question).

This sentence is in Past indefinite. The auxiliary verb of Past Indefinite is the second form of to do did. We use the auxiliary verb when we form General question.