What are Two features that make the Nile river very hard to navigate?

The Nile River has been a central feature of life in northeast Africa for ... Its three main tributaries are the White Nile, the Blue Nile, and the Atbara. ... Sea is rich in nutrients, due to the large silt deposits the Nile leaves ... and rope, but by far its most important use was in making paper.

copernicus finished the first manuscript of his book, "de revolutionibus orbium coelestium" ("on the revolutions of the heavenly spheres") in 1532. in it, copernicus established that the planets orbited the sun rather than the earth. he laid out his model of the solar system and the path of the planets.

the poor lived on the docks by the sea, and the wealthy lived in highly populated urban areas. that is the answer