A man Rollerblades on a skate course.
The man is in a race.
Not everyone who skates on a course will be in a race.
exists e1 s1 x1 x2.(on(e1,x2) & n_course(x2) & a_skate(s1) & Theme(s1,x2) & Actor(e1,x1) & v_rollerblade(e1) & n_man(x1))
exists p1 x1.(n_man(x1) & exists x2.(in(x1,x2) & n_race(x2)))