These three people are playing instruments while sitting in front of sheet music stands.
Three people play music off of sheets.
Three musicians are playing instruments, as such they need music on music stands in order to remember all of the notes.
exists e1 e3 e2 x1 x2 x3 x4 x5 x6.(n_people(x1) & card_eq_3(x1) & while(e1,e2) & in(e2,x3) & of(x3,x4) & Actor(e3,x6) & v_stand(e3) & (x4 = x6) & n_music(x4) & of(x4,x5) & n_sheet(x5) & n_front(x3) & Actor(e2,x1) & v_sit(e2) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_instrument(x2))
exists e1 x1 x2 x3.(of(e1,x3) & n_sheet(x3) & r_off(e1) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_music(x2) & n_people(x1) & card_eq_3(x1))