What's unique about underground mining

Each underground mine is unique, but they all have at least a few things in common. They all have access shafts for workers and equipment, recovery shafts to bring excavated rocks to the surface, and ventilation shafts. They also all rely on a communication system between the depths of the mine and the surface. 5.

Explanation:

what are local authorities doing to fix the problem

explanation:

the federal constitution of the united mexican states of 1824 was enacted on october 4 of 1824, after the overthrow of the mexican empire of agustin de iturbide. in the new constitution, the republic took the name of of united mexican states. it was replaced by the federal constitution of the united mexican states in 1857.