Final answer:
Poland and Czechoslovakia are the two countries that grew larger after WW1, with Poland gaining land from Germany and Czechoslovakia being formed from the Austro-Hungarian Empire.
Step-by-step explanation:
Of the countries that existed in 1914, the two countries that grew larger after WW1 thanks to land taken from Germany were Poland and Czechoslovakia. These territories were gained as a result of the peace treaties that redrew the map of Europe following the end of the conflict. Germany had to cede territory on its eastern side to the re-established nation of Poland, while Czechoslovakia was formed from the Austro-Hungarian Empire rather than directly from German lands. The Treaty of Versailles and other allied agreements led to these changes.