The correct statements that describe aspects of the Aztec civilization are:
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practiced human sacrifice to keep Huitzilopochtli strong - The Aztecs performed human sacrifices as a religious practice to appease their gods, including Huitzilopochtli, the god of war and the sun.
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predicted eclipses and developed a 365-day calendar - The Aztecs created sophisticated calendars, including a 365-day solar calendar, which helped them track agricultural and ceremonial events.
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capital city with a population larger than any European city of the time - Tenochtitlán, the capital of the Aztec Empire, was one of the largest cities in the world at the time, with a population that exceeded that of contemporary European cities.
The statement regarding communicating using runners from the capital city of Cuzco is incorrect, as Cuzco was the capital of the Inca Empire, not the Aztec Empire. The Aztecs did have a system of runners known as "tamemes" to relay messages and goods across their empire.