A middle-aged Caucasian man is driving a postal van.
A man sits behind the wheel of a vehicle.
A vehicle is implied when it stated that the man was driving a postal van.
exists e1 s1 s2 s3 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_drive(e1) & n_van(x2) & a_postal(s3) & Theme(s3,x2) & n_man(x1) & a_caucasian(s2) & Theme(s2,x1) & a_middle-aged(s1) & Theme(s1,x1))
exists e1 x1 x2 x3.(n_wheel(x2) & behind(e1,x2) & of(x2,x3) & n_vehicle(x3) & Actor(e1,x1) & v_sit(e1) & n_man(x1))