Muslims translated Greek books into Arabic. How would this help preserve Greek
knowledge?

Explanation:

By translating their knowledge into other languages they have a  whole new group of people who can read their works because it's in their language so they can read it. Making their thoughts and belifs spread to other languages therefore spreading it to nations who speak that language.

Having a ziggurat signified that city was large and important. 

If any city had a ziggurat, it meant that they were big and important. People in the city believed the ziggurats were the dwelling places of the gods. Each big city had its own patron god, close to human kind.