Past. You are talking about what already happened
Nick was referring to the discovery of George's body. Holocaust is defined as a slaughter...... Myrtle, Gatsby, and Tom had each lost their lives for nothing....... they were the sacrifice of those who didn't care for anything or anyone beyond themselves.
Hope this helps!
To put abstract ideas into close-up words or a description that is more easily understood. Use D) concrete descriptions. Concrete descriptions seek to make a concept easily understood by the reader or listener.