【正确答案】正确答案： Border A border is a real or artificial line that separates geographic areas. / Borders are political boundaries. / They separate countries, states, provinces, counties, cities, and towns. / A border outlines the area that a particular governing body controls. / Borders—particularly national borders—affect travel and migration. / People can usually move freely within their own country's borders, / but may not be allowed to cross into a neighboring country. / When neighboring countries have similar wealth and political systems, / their borders may be open and undefended. / For example, citizens of the 27-country European Union may travel freely among any of the member states. /