Man is doing a trick while skiing on the lake.
A man is inflating a raft.
He can't inflate a raft while doing a skiing trick on the lake at the same.
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_inflate(e1) & n_raft(x2) & n_man(x1))