A boy is throwing a baseball.
A boy throwing a baseball.
A boy is throwing a baseball, instead of just throwing.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_throw(e1) & n_baseball(x2) & n_boy(x1))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_throw(e1) & n_baseball(x3) & (x1 = x2) & n_boy(x1))