1. David had gone home before we arrived. (after)  2. We had lunch then we took a look around the shops. (before)  3. The light had gone out before we got out of the office. (when)  4. After she had...

1. After we arrived, David had already gone home. 2. Before we took a look around the shops, we had lunch. 3. When we got out of the office, the light had already gone out. 4. By the time she had explained everything clearly, we started our work. 5. Before my mother came home, my father had watered all the plants in the garden.