Answer: An aquifer is defined as a body of rock or unconsolidated sediment that has sufficient permeability to allow water to flow through it. Unconsolidated materials like gravel, sand, and even silt make relatively good aquifers, as do rocks like sandstone. Other rocks can be good aquifers if they are well fractured.
Saudi Arabia produces oil in very large amount and it leads the oil market.
The United states is an example of a democratic government.
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High density of people in Hong Kong, New york City, all big citys in India like Delhi or calcuta
