Цей матеріал буде корисним під час пояснення правил утворення та вживання the Past Perfect Tense.
Put the sentences into negative form: I couldn’t open the door because I had lost my keys. Ann had gone to the USA before she left school. He had read that book by Saturday. Ask questions: They had received his letter by Monday. She had paid a lot of money by that time. He had given me some money by 6 o’clock.