What percentage of the earth's water is in the form of groundwater?

What was the great rift valley formed by

Which two following best identify the central themes of this speech in the passage the man in the arena

What's a recharge area? a. the part of an aquifer where groundwater meets a lake or stream b. the part of an aquifer where surface water reaches the water table c. the part of an aquifer that's located between two aquicludes d. the part of an aquifer that's located at a lower elevation