Answer:
1. We wait/are waiting in the park.
2. I hear the concert.
3. You lose your patience.
4. He visits/is visiting his mother.
5. They answer the question.
6. Claude sells some books.
7. The lawyer defends the criminal.
8. She returns the book to the library.
9. You correspond with a friend in France.
10. You descend the staircase/stairs very rapidly.
Explanation:
