I believe the answer you are looking for is the "Neolithic Period".
Answer:
Freshwater, Ocean Water, and Terrestrial.
Explanation:
These are the broadest 'three types of ecosystems' that come to mind.
Answer:
Around the world the most significant restriction on access to potable water is money. While access to raw water sources, clean or otherwise, is important, the purification process itself is expensive. Once water has been rendered potable, it is important that it be delivered without reintroducing contamination.
Answer:
The path of a total eclipse that is swept out by the umbra shadow of the moon on the earth. The umbra is the dark center portion of a shadow. The Moon's umbra causes total solar eclipses, and the Earth's umbra is involved in total and partial lunar eclipses.
I hope this helps
