A person is doing a flip in midair near a lake with sails behind him.
The person is sitting on a boat.
The two sentences contradict each other based on that one who is sitting can not also be completing flips in midair.
exists e1 x1 x2 x3 x4 x5.(with(e1,x5) & behind(x5,x1) & n_male(x1) & n_sail(x5) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & in(x2,x3) & near(x3,x4) & n_lake(x4) & n_midair(x3) & n_flip(x2) & n_person(x1))
exists e1 x1 x2.(n_person(x1) & on(e1,x2) & n_boat(x2) & Actor(e1,x1) & v_sit(e1))