Final answer:
The Czech Republic, Hungary, the Slovak Republic, and Poland are members of the European Union (EU). These countries transitioned from communism and pursued integration into the international community, with Poland and Hungary proactively joining several global organizations.
Step-by-step explanation:
The Czech Republic, Hungary, the Slovak Republic, and Poland have become members of the European Union (EU). This expansion included various countries that transitioned from communism to democracy and sought to join international organizations to integrate more with the global community. For instance, the Czech Republic and Slovakia, previously part of Czechoslovakia, became independent in 1993 and later joined the EU. Hungary has been particularly active in joining international groups like the EU, the Organization for Economic Co-operation and Development (OECD), the International Monetary Fund (IMF), and the World Trade Organization (WTO) since shifting from communism. Poland, which re-emerged as a nation after previous partitions, has also joined the EU, marking its integration into the European community.