A boy is rock climbing.
A boy is eating a pizza.
Rock climbing & eating pizza are two different activities.
exists p1 x1.(exists x2 x3.((x1 = x2) & n_climb(x2) & of(x2,x3) & n_rock(x3)) & n_boy(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_eat(e1) & n_pizza(x2) & n_boy(x1))