What did the Russian army discover when they pushed Poland into Germany?

Ireally need on this homework! if you get it right so much if not its fine < 3 ! (i have no points so sorry its only 10)i didnt mean to put it on social studies sorry!

How does specialization enable countries to trade with one another? a country can make and sell goods affordably and buy goods that it is inefficient at making. a country can make what it chooses and sell its goods to other countries. a country can decide to buy everything it needs from other countries. a country can efficiently make goods that were once difficult to make.

When the communist, under mao, took control of china in 1949 they announced total support support for which country and its ideology?