A boy in an orange snorkel mask swims underwater.
A kid swimming.
boy swims underwater is same as kid swimming
exists e1 x1 x2 x3 x4 x5.(Theme(e1,x5) & Actor(e1,x1) & v_swim(e1) & n_underwater(x5) & in(x1,x2) & n_mask(x2) & of(x2,x4) & n_snorkel(x4) & of(x2,x3) & n_orange(x3) & n_boy(x1))
exists x1 x2.(a_topic(x1) & n_swimming(x1) & of(x1,x2) & n_kid(x2))