A repairman is working on a train.
The repairman is doing some preventative maintenance to the train.
It cannot be inferred that the man working on the train is doing preventative maintenance.
exists e1 x1 x2.(on(e1,x2) & n_train(x2) & Actor(e1,x1) & v_work(e1) & n_repairman(x1))
exists e1 s1 x1 x2 x3.(n_train(x3) & n_repairman(x1) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & to(x2,x3) & n_maintenance(x2) & a_preventative(s1) & Theme(s1,x2))