Present Perfect. Change the sentences to negative.

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

2. She has been sick lately.

3. I have called her today.

4. He has failed to get their attention.

5. She has put on a black dress.

6. We have worked on this together.

7. They have missed their chance.

8. He has exercised this week.

9. I have tried to reach him.

10. It has been easy.