sentence: Several young men practice long jumps, and backward jumps inside of a gym with an American Flag hanging on the wall. sentence:   A man practices a long jump inside of an indoor gym using a interior sandbox  for landing and a drawn race track isle. sentence:   Another man practices hurling himself backward over a pole onto a gym mat inside of the gym. sentence:   Several more men practice long jumps and backward jumps inside of the gym using the sandbox and gym mats as landing tools.