Adult and child observe fish tank.
a man and son watch a fish tank in the waiting room
The adult and child could be acquaintances and not necessarily a man and son. Fish tanks are commonly in waiting room but they can be in many other places as well
exists s1 x1 x2 x3 x4 x5.(n_tank(x1) & of(x1,x5) & n_fish(x5) & of(x1,x4) & n_observe(x4) & of(x1,x3) & n_child(x3) & a_.(s1) & Theme(s1,x1) & of(x1,x2) & n_adult(x2) & a_topic(x1))
exists e1 x1 x2 x3 x4 x5 x6 x7.(n_room(x6) & of(x6,x7) & n_waiting(x7) & in(e1,x6) & Theme(e1,x4) & Actor(e1,x1) & v_watch(e1) & n_tank(x4) & of(x4,x5) & n_fish(x5) & n_son(x3) & n_man(x2) & subset_of(x3,x1) & subset_of(x2,x1))