He movement of a substance from a small space to a larger space

the gradient pressure in the small space,builds up to a point where the liquid will overflow or move to a larger space..

a historian who compares the expansion of political systems to the expansion of economic systems to the expansion of economic systems is organizing history by theme.

hope this : d

shang dynasty

western zhou (ca. 1046-771 bce)

eastern zhou (ca. 771-256 bce)