Ответ:

1. When I came the lecture had already started.

2. They had already translated this text last lesson.

3. When I came he hadn't left yet, so we only had time for a few words.

4. When we came to the airport, the plane had already landed.

5. He suddenly understood that he had travelled in the wrong direction.

6. When Ann had finished her homework she turned on TV.

Объяснение: