Present perfect. Change the following sentences to questions.

1. They have been here before.

2. Trent has finished cleaning.

3. They have left.

4. She has tried to contact you.

5. They have solved the problem.

6. They have started playing.

7. Quincy and Janet have worked together.

8. It has stopped working.

9. Faruk has lived in this town all his life.

10. I have seen this show.