There are many natural processes that shape the Earth's surface. These processes can act as constructive forces, destructive forces, or both. In general, natural processes act as destructive forces
A.
only at high elevations.
B.
when they build up landforms.
C.
when they wear down landforms.
D.
only at sea level.

Where did the term “iron curtain” originate? the warsaw pact used the term iron curtain as a code word for communism. in a 1946 speech, british prime minister winston churchill said an iron curtain had fallen across the continent of europe. while visiting western europe in 1946, u.s. president harry truman commented that the mountains there looked like iron curtains. russian general secretary joseph stalin instructed citizens of eastern europe to hang iron curtains over their windows to protect themselves from stray bullets.