Because many rivers run swiftly down int mountains.
Hope that helps
The right answer for the question that is being asked and shown above is that: "Governments did not get involved – and allowed farmers to grow whatever they pleased." Governments and international organizations cut down on the number of opium farms is that governments did not get involved – and allowed farmers to grow whatever they pleased<span>
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The North Atlantic Drift, which originates as the Gulf Stream next to Florida, brings warm water in the direction of Europe, over the Atlantic.
It means that Europe is warmer than it would be without it, more similar to the land at the same latitudes, such as Siberia and Canada, which has a lot harsher climate
in short, it has a warming effect.