A person taking a jump off a rock on a dirt bike.
A man is showing off in front of his friends
The man may not be showing off.  The man may not be in front of his friends.
exists e1 x1 x2 x3 x4 x5 x6.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_take(e1) & on(x3,x5) & n_bike(x5) & of(x5,x6) & n_dirt(x6) & off(x3,x4) & n_rock(x4) & n_jump(x3) & (x1 = x2) & n_person(x1))
exists e1 s1 x1 x2 x3.(in(e1,x2) & of(x2,x3) & n_friend(x3) & of(x3,x1) & n_male(x1) & n_front(x2) & a_off(s1) & Manner(e1,s1) & Actor(e1,x1) & v_show(e1) & n_man(x1))