Can some explain to me what is sea floor spreading? keep it simple and brief < 3

Why does sweden and norway have steep roofs

Based on what you know about the location of the earth in relation to the sun, why is this called the goldilocks zone in other galaxies? a. it's a region that exhibits a weak gravitational pull, thus maintaining a safe distance from the sun. b. it's an area that doesn't experience any major weather events that could cause mass extinctions. c. it's an area that's an optimal distance from the sun for potentially supporting life. d. it's a region that's unaffected by asteroid or meteor impacts.

Which ecosystem best fits the characteristics listed below? which ecosystem best fits the characteristics listed below? ii. seasonal migrations of millions of wildebeests, zebras, and elephants iii. large numbers of predators, such as lions iv. acacia trees and grasses a. the congo rainforest b. the african mangroves c. the serengeti grasslands d. the sahel