Final answer:
Sentence 4 is the foreshadowing sentence because it hints at Doodle's absence in the narrator's life.
Step-by-step explanation:
The sentence from the excerpt that is foreshadowing is sentence 4. This is because it hints that Doodle is no longer present in the narrator's life. The mention of the grindstone turning and the narrator remembering Doodle suggests that Doodle's absence is significant and may have had a tragic outcome. This foreshadows a potential twist or revelation later in the story.
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