Present Perfect. Change the sentences to negative.

1. She has put on a black dress.

2. He has failed to get their attention.

3. It has been easy.

4. She has been sick lately.

5. We have worked on this together.

6. I have tried to reach him.

7. We have known each other for a long time.

8. I have called her today.

9. He has exercised this week.

10. They have missed their chance.