A mailman in his truck whom is in front of a gate.
A mailman sits in a truck.
in his truck refers to sits in a truck.
exists p1 x1 x2 x3.(exists x4 x5.(in(x1,x4) & of(x4,x5) & n_gate(x5) & n_front(x4)) & in(x1,x2) & n_whom(x2) & of(x2,x3) & n_truck(x3) & of(x2,x1) & n_male(x1) & n_mailman(x1))
exists e1 x1 x2.(in(e1,x2) & n_truck(x2) & Actor(e1,x1) & v_sit(e1) & n_mailman(x1))