1.She said the children had been playing since they went out.
2. Tim had been making the same spelling mistakes since I started teaching him.
3. We had been corresponding since I moved to this town.
4. How long had she been studing French before she left for Paris?
5. The children is so dirty. He has been playing in the wet sand since morning.
6. My eyes are aching. I have been reading the report for the whole afternoon.
7. By the time we finish the tenth form, we have been writing a lot of essays and summaries