Why did so many early civilizations arise near river valleys?

Which area of russia is volcanically active? a. ural mountains b. baltic sea c. kamchatka peninsula d. volga river

Soon-yi's house has a hexagonal window made up of six identical equilateral triangles as pictured below.

Two gymnastics teams are intense rivals. the first team has started recruiting new gymnasts from different cities and even foreign countires in an effort to build a stronger team. after learning this, the secondteam begins its own recruitment campaign to find better gymnasts. over a period of months, each team recruits dozens of players, each time trying to find a better recruit than its rivals most recent addition. which idea from the cold war is most similar to this scenario