Answer:
Mechanics, each one singing his as it should be, blithe and strong
•Young fellows, robust, friendly
Explanation:
Parallelism occurs when balance is given to phrases within a sentence that have the same structure.
An adjective is a part of speech that is used to describe a noun or a pronoun in a sentence.
Therefore, the texts in the passage from "I Hear America Singing" by Walt Whitman that uses adjectives to enhance the effects of parallelism are "Mechanics, each one singing his as it should be, blithe and strong
•Young fellows, robust, friendly"
The main idea of the paragraph would be the penguins camouflage and feathers help them in their survival
3 supporting facts would be: it makes them hard to see in the ocean for predators, they blend with they sky, their feathers protects them while swimming and keeps them warm.
(this could be worded better but yeah, hope I could help!)