Here are some examples from Hemingway’s "In Another Country" that demonstrate parallelism:
The hospital was very old and very beautiful.
In this first example, the word very before the word old and again before the word beautiful helps maintain the balance of the sentence.
The girls at the Cova were very patriotic, and I found that the most patriotic people in Italy were the café girls—and I believe they are still patriotic.
The word patriotism is repeated three times in this example. Patriotism is one of the important themes of the story.
The three with the medals were like hunting-hawks; and I was not a hawk, although I might seem a hawk to those who had never hunted.
Finally, the word hawk is repeated three times to emphasize how different the speaker was from the other boys. This repetition emphasizes the alienation that the speaker felt in Milan.