Two people are making an exchange.
The exchange involves drugs
It's not necessarily they are exchanging drugs.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_make(e1) & n_exchange(x2) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2.(n_exchange(x1) & Theme(e1,x2) & Actor(e1,x1) & v_involve(e1) & n_drug(x2))