Final answer:
The calm lake was a mirror
Step-by-step explanation:
The example of the literary device metaphor is: The calm lake was a mirror. A metaphor is a figure of speech that compares two things without using the words 'like' or 'as'. In this example, the calm lake is compared to a mirror, suggesting that it was so still and reflective that it appeared like a mirror.
Learn more about Examples of metaphor