A boy does a trick on his bike as other kids watch.
A human rides a bike.
A boy is a type of human and to do a trick on a bike means you are riding a bike.
exists e1 e2 x1 x2 x3 x4 x5 x6 x7.(n_kid(x6) & Theme(e2,x7) & Actor(e2,x1) & v_watch(e2) & n_thing(x7) & as(e1,x5) & -(x5 = x6) & n_kid(x5) & on(e1,x4) & n_bike(x4) & of(x4,x1) & n_male(x1) & Theme(e1,x3) & Actor(e1,x2) & v_do(e1) & n_trick(x3) & (x1 = x2) & n_boy(x1))
all x1.(n_bike(x1) -> exists s1 x2.(a_topic(x2) & for(x2,x1) & n_ride(x2) & a_human(s1) & Theme(s1,x2)))