試題詳解

33.
(A) Then, GPS units to work out where we are standing and which drivers are coming our way.
(B) The next step is equipping a critical mass of passengers and vehicles for it to be a practical option.
(C) But the technological solution to this problem is already close at hand.
(D) To make our hitchhiking future happen, we’re going to need help overcoming the significant social and cultural barriers.