A man playing a white guitar with sheet music.
The man is practicing a song he does not yet know.
Just because someone is using sheet music doesn't mean that they are practicing a song they do not yet know.
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & with(e1,x4) & n_music(x4) & of(x4,x5) & n_sheet(x5) & Theme(e1,x3) & Actor(e1,x2) & v_play(e1) & n_guitar(x3) & a_white(s1) & Theme(s1,x3) & (x1 = x2) & n_man(x1))
exists e1 x1 x2.(n_male(x1) & n_man(x1) & Theme(e1,x2) & Actor(e1,x1) & v_practice(e1) & -exists e2 s1 x3.(a_yet(s1) & Manner(e2,s1) & Theme(e2,x3) & Actor(e2,x1) & v_know(e2) & (x2 = x3)) & n_song(x2))