Why did the chinese call their country the middle kingdom?

How and why did british north american colonists fight a revolution to create a constitutional republic, the united states of america?

What do most climatologists see as a major cause of rising global temperatures? a. earth's closer proximity to the sun due to its gravitational pull b. greenhouse gases produced by burning fossil fuels c. rising ocean levels caused by melting polar ice sheets d. water pollution cause by industrial waste

What are some of the difficulties that the japanese face due to the islands' geography?