Questions

There are about 1,000,000 nephrons in each human kidney.

Nephron, functional unit of the kidney, the structure that actually produces urine in the process of removing waste and excess substances from the blood.

Representative money is an item such as a token or piece of paper that has no intrinsic value but can be exchanged on demand for a commodity that does have intrinsic value, such as gold, silver, copper,...

Hence, a Check is an example of representative money.

rift valley

Gear Lapping is an operation after heat treatment. Gear lapping is the process of imparting a very fine finish and high degree of accuracy to gear teeth, by using a lapping tool and applying a fine-grained abrasive between a work material and a closely fitting surface, called a lapping plate.