Ans 1: Specialization is doing particular tasks rather than doing all jobs by oneself. Division of labor is dividing an operation into many small tasks to be performed by specialized labor and machines.
Ans2: China, and Denmark.
Ans3: Civilizations developed around rivers because their waters provided places to hunt and fish. Also, as the rivers flooded, the lands around them became fertile. This allowed them to support farming. This is especially true of the Nile River, which flooded the same time each year.
