Final answer:
The narrator thought his father had died because his father's body was still and his eyes were half-open with a glassy look.
Step-by-step explanation:
The narrator in the given passage thought his father had died because his father's body was still and his eyes were half-open with a glassy look. The fact that the father was breathing faintly and not responding to the narrator's actions made him believe that his father had passed away.
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