These sentences correspond to the following plots:
"She clasped her sister's waist, and together they descended the stairs." - This sentence describes a moment of resolution and reconciliation between two characters who may have been in conflict earlier in the story. It could appear at the end of a story, after a climax has been resolved, or in the middle of a story, when characters are coming together to face a common challenge.
"When the doctors came they said she had died of heart disease-of the joy that kills." - This sentence describes the moment when a character learns of the death of someone close to them. It could appear near the end of a story, as part of a resolution or denouement, or it could be a turning point in the story that leads the character on a new path.
"It was Brently Mallard who entered, a little travel-stained, composedly carrying his grip-sack and umbrella. He had been far from the scene of the accident, and did not even know there had been one." - This sentence describes the moment when a supposedly dead character returns, surprising other characters who had believed them to be dead. It could be a turning point in the story that changes the direction of the plot, or it could be a climactic moment that resolves earlier conflicts.
"He stood amazed at Josephine's piercing cry: at Richards' quick motion to screen him from the view of his wife." - This sentence describes the moment when a character learns of a shocking revelation or event, and their perception of the world is shattered. It could be a turning point in the story that leads the character on a new path, or it could be a moment of realization that brings the story to its climax...