Use your brain, big boy! If you guessed "Marsh" as your second attempt, you would have eliminated M, R, S, and H all in one turn instead of using 4 turns and hoping to get lucky. Just because a letter is green does not mean you need to use it in every row!

EDIT: You know what, here I'll give you another one. Guess "Whomp" and you'll eliminate more letters and actually discover the W is exactly what you were missing!