A man wearing a gray shirt is tuning his guitar.
A man is putting a mouthpiece on a trumpet.
A man tuning his guitar is not the same as putting a mouthpiece on a trumpet.
exists e1 e2 s1 x1 x2 x3 x4.(Theme(e2,x4) & Actor(e2,x1) & v_tune(e2) & n_guitar(x4) & of(x4,x1) & n_male(x1) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_shirt(x3) & a_gray(s1) & Theme(s1,x3) & (x1 = x2) & n_man(x1))
exists e1 x1 x2 x3.(on(e1,x3) & n_trumpet(x3) & Theme(e1,x2) & Actor(e1,x1) & v_put(e1) & n_mouthpiece(x2) & n_man(x1))