A boy is skateboarding in a skateboard park.
The boy is sitting at his house
The boy cannot be skateboarding and sitting at the same time.
exists e1 x1 x2 x3.(in(e1,x2) & n_park(x2) & of(x2,x3) & n_skateboard(x3) & Actor(e1,x1) & v_skateboard(e1) & n_boy(x1))
exists e1 x1 x2.(n_house(x2) & of(x2,x1) & n_male(x1) & n_boy(x1) & at(e1,x2) & Actor(e1,x1) & v_sit(e1))