<span><span>The BEST
answer is </span>Social and
economic differences promote a different kind of cultural development on either
side of the border. </span>
Boundaries restrict movement between
the two ethnic groups. This results to accumulation of differences in social
and economic activities due to relative exclusivity until they are well pronounced to be perceptible.
71 percent of the Earth's surface is covered with water. The visible bodies of water are referred to as surface water and water found underground as soil moisture and in aquifers is referred to as groundwater. <span>Humans use both ground and surface water.</span>
20% of the world's freshwater supply comes from groundwater and 80 % from surface water.
More citizens protested against the soviet government.
The unsuitable factors for forming is '' salt,paints,poisnes substances,etc"