A. Sections of the Grand Canal were connected, improving trade and communication. B. A desire to read Buddhist scriptures led to the invention of printing.

C. The characteristics of Chinese culture were firmly established.

D. Military engineers developed gunpowder and explosive rockets.

E. Public schools were opened. Civil service exams were used to recruit qualified officials.

F. Chinese society was divided into four classes.

Yuan
Song
Tang
Han
Sui
Ming