Final answer:
The author uses diction to reveal the setting by creating a sense of time and place in Brooklyn before the First World War, as well as the nostalgic and tender feelings associated with Thanksgiving Day.
Step-by-step explanation:
The author uses diction such as "First World War" and "Thanksgiving Day" to reveal the setting in the excerpt from A Tree Grows in Brooklyn. The specific words and phrases chosen help to create a sense of time and place in Brooklyn before the war, as well as the nostalgic and tender feelings associated with Thanksgiving Day during that time.