When did armies of christians travel to the holy land seeking to regain control of the holy lands?

Which best describes the idea behind the "invisible hand"? producers decide what to make for consumers, which guides the economy. individuals seeking their own self interest benefit the economy as a whole. government sets policy for producers and consumers, which guides the economy. consumers decide what they need and want to buy, which guides the economy.

Why learning about people and places around is important?

What happens after a star goes supernova? just wondering! [tex]supernova [/tex] answer asap i really wanna know!