Final answer:
Passages revolve around the dramatic action of locking a door and its implications on the narrative and characters in various English literary texts and plays.
Step-by-step explanation:
The passages provided come from various literary texts and plays, suggesting an exercise in English literature analysis or drama class activities. The central theme revolves around the action of locking a door, which serves as an important plot device in different narratives. The characters' interactions with the locked door contribute to the tension and development of the storyline. For instance, the text where Professor Plum blocks the study door by declaring it 'occupied' provides a dramatic moment that could be further explored in a literary analysis or discussed in the context of character development. Similarly, other excerpts depict characters who lock doors to assert control, create privacy, or elicit specific reactions from other characters.