A man is skiing in water.
A man is doing tricks while skiing.
Skiing does not imply doing tricks.
exists e1 x1 x2.(in(e1,x2) & n_water(x2) & Actor(e1,x1) & v_ski(e1) & n_man(x1))
exists e1 x1 x2 x3.(while(e1,x3) & n_skiing(x3) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_trick(x2) & n_man(x1))