Man is doing a trick while skiing on the lake.
A man is performing a stunt.
A trick can be a stunt also.
exists e1 x1 x2 x3 x4.(n_lake(x4) & on(e1,x4) & while(e1,x3) & n_skiing(x3) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_trick(x2) & n_man(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_stunt(x2) & n_man(x1))