Man working on old truck while child watches.
A child fixing a truck while a man watches.
The man is working and a child watches, whereas a child fixing and a man watches implies people performing the opposite of their original activity.
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & while(e1,x4) & n_watch(x4) & of(x4,x5) & n_child(x5) & on(e1,x3) & n_truck(x3) & a_old(s1) & Theme(s1,x3) & Actor(e1,x2) & v_work(e1) & (x1 = x2) & n_man(x1))
exists e1 p1 x1 x2 x3.(a_topic(x1) & exists e2 x4.(Actor(e2,x4) & v_watch(e2) & n_man(x4)) & while(e1,p1) & Theme(e1,x3) & Actor(e1,x2) & v_fix(e1) & n_truck(x3) & (x1 = x2) & n_child(x1))