The Danube River forms the border of some countries. They are Romania, Bulgaria, Hungary, Serbia, Slovakia, Austria and Germany.
Slovakia and Hungary
Its the Danube river and Danube plain separates Romania and Bulgaria. There are no mountaneous border between the mentioned two countries. And Carpathian mountain range of Romnia or Balkan mountain range (most northern mountains of Bulgaria: none of them serves as border.
river Danube (река Дунав)
The Danube.
The two countries that border Andorra are Spain and France.
This river is called Danube. Its a northern border to Bulgaria and for Romania the south bound.
The two countries that border Somalia are Ethiopia and Kenya.
Canada and Mexico are the two countries that border the United States.
Do you mean countries? If you do, the two countries that border the U.S. are Canada and Mexico.
The two countries on Iraq's southern border are Saudi Arabia and Kuwait.
Bolivia and Paraguay are the only two countries in South America that do not border on an ocean.