Answer:
developed complex mathematical and calendar systems.
Explanation:
Proven answer from test answer book :D
During the Civil War, "Copperheads" referred to B. NORTHERN SUPPORTERS OF THE CONFEDERACY.
The Copperheads were those vocal democrats located in the Northern United States of the Union who were opposed to the American Civil War. They wanted to have an immediate peace settlement with the confederates.
The Republicans were the ones who called these antiwar democrats "copperheads"; likening them to the venomous snake.
The thirteenth amendment freed slaves, and Abraham Lincoln wrote the emancipation proclamation which freed slaves in the south
Here are the matches:
<span>1- The Soviet Union invaded Czechoslovakia and reversed its economic reforms, D.1968
</span><span>2-Workers in Poland won higher wages after an uprising. B. 1956
</span><span>3-Yugoslavia parted ways with the Soviet Union because of political differences. A. 1948
</span><span>4-Military forces began constructing the Berlin Wall. C.1961
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All of these events keep strengthening the west's relation with these countries and weakened Soviet Union's position even among its neighboring countries.
