A skateboarder flips his board over some steps in a plaza.
A skateboarder walks across the plaza with his board in hand.
A person cannot flip his board while walking
exists e1 x1 x2 x3 x4.(Theme(e1,x2) & Actor(e1,x1) & v_flip(e1) & over(x2,x3) & in(x3,x4) & n_plaza(x4) & n_step(x3) & n_board(x2) & of(x2,x1) & n_male(x1) & n_skateboarder(x1))
exists e1 x1 x2 x3 x4.(n_board(x3) & of(x3,x2) & n_male(x2) & n_plaza(x2) & with(e1,x3) & in(x3,x4) & n_hand(x4) & across(e1,x2) & Actor(e1,x1) & v_walk(e1) & n_skateboarder(x1))