Final answer:
A mix-up in the reference provided makes it difficult to answer the question about Christopher and Mrs. Shears directly, but in a related context from Mark Haddon's novel, Christopher is highly concerned with who killed Wellington, the dog.
Step-by-step explanation:
The student is asking about the interactions of characters in a specific context, where one character, Christopher, repeatedly asks Mrs. Shears for something after she makes him promise not to tell his father something. However, there is a mix-up in the reference provided.
The excerpts given are from various literary works that do not involve a character named Christopher or Mrs. Shears directly. But based on the known plot of the novel The Curious Incident of the Dog in the Night-Time by Mark Haddon, it's likely that Christopher continuously asks Mrs. Shears who killed Wellington, the dog, as this is a central concern for the character throughout the story.
Since the question appears to be related to a different story, we cannot provide a direct answer without the correct context.Based on the given information, it is unclear which specific text or story is being referred to in the question. In order to provide an accurate answer, please provide more context or clarify the text or story in question.