The point of this puzzle is to find a letter for each of the list on the left that completes a common word. Then use those same letters to complete the list on the right.
Hints & Solutions Edit
You may be having trouble fitting a single letter into the blank spaces, but rest assured a single letter does fit into each blank.
They never said it was an English letter you had to insert...
Did you ever pledge to a Fraternity or Sorority in college?
The "single letter" inserted into the first blank is the Greek letter "CHI" (pronounced "kai" in English).
The full solution to the Left and Right word list plus the solution is found in the next block of text. If you do not wish to be spoiled, please do not continue.
Keyword: CHI + RHO = CAIRO (kai + row)