upstream
adv, adj in the directionfrom which a river, etc flows; against the current 向上游(的); 逆流(的)
row, swim, walk upstream 往上游划、 游、 行走
Factories upstream (from us) are polluting the water. 在(我们)上游的工厂污染了河水. Cf 参看 downstream.
Twenty or thirty pages of information handed to any of the major world powers around the year 1925 would have been sufficient to change the course of world history.