A mechanic in blue coveralls works on a bus.
A mechanic is wearing coveralls at work.
When someone works they are usually at work.
exists e1 s1 x1 x2 x3.(on(e1,x3) & n_bus(x3) & Actor(e1,x1) & v_work(e1) & in(x1,x2) & n_coverall(x2) & a_blue(s1) & Theme(s1,x2) & n_mechanic(x1))
exists e1 x1 x2 x3.(at(e1,x3) & n_work(x3) & Theme(e1,x2) & Actor(e1,x1) & v_wear(e1) & n_coverall(x2) & n_mechanic(x1))