A man on a skateboard poses with a dog.
The man is riding a bike
A person who is riding a bike can not be on a  skateboard  at the same time.
exists e1 x1 x2 x3.(with(e1,x3) & n_dog(x3) & Actor(e1,x1) & v_pose(e1) & on(x1,x2) & n_skateboard(x2) & n_man(x1))
exists e1 x1 x2.(n_man(x1) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2))