1. If they (work) hard last year, they (earn) much money. But they didn't.(3)

If they **had worked** hard last year, they **would have earned** much money. But they didn't. *Explanation: This is a third conditional. It describes an unreal past situation and its hypothetical result. We use 'had + past participle' in the 'if' clause, and 'would have + past participle' in the main clause.* *Перевод: Если бы они усердно работали в прошлом году, они бы заработали много денег. Но они этого не сделали.*