Discharge time this hydrograph represents the discharge of a river over a year long time period. based on this, which of these statements is most likely to be true. the river is overlying granite the river is overlying a sandy deposit the river is primarily sourced by throughflow the river is in a field

81 is a composite number

The sun's parallax would be 180 degrees, greater than which you can't get.  so a. would be your anwser 

Humans have survived and thrived in mexico city by using technology to create greater access to land. when the spanish conquered the aztec capital, tenochtitlan, in the 16th century, they built mexico city by draining the lakes and filling in the lake water to create more arable land for agriculture. this technique of land reclamation has continued to be fundamental to human civilization in mexico city.