Below is a partially filled in grid of letters that form a crossword-style set of ten 5-letter words, 5 across and 5 down.
Add the following set of letters to the empty cells so that the set of ten different words is complete:
D, F, G, G, H, O, P, R, R, R, R, S, T, T, U
From Mensa Puzzle Calendar 2017 by Mark Danna and Fraser Simpson, Workman Publishing, New York. Puzzle for July 12.