Here are the completed sentences for the prompts you've provided:

18. “I’m sorry I broke the glass," said Peter.
Peter apologized for breaking the glass.

19. “Why don't you put your luggage under the seat?" he asked.
He suggested that she put her luggage under the seat.

20. “It's true that I broke the old vase," she said in tears.
She admitted that she broke the old vase.

21. “Don’t move or I will shoot," said the bank robber to the clerk.
The bank robber threatened the clerk.

22. “Don’t forget to phone the police," she told him.
She reminded him to phone the police.

23. “Don’t swim out too far, boys," said the coach.
The coach warned the boys not to swim out too far.