How did chinese dynasties use an imperial bureaucracy to maintain and justify rheir rule?

They conducted efficient civil service exams to recruit the best bureaucrats.

Explanation:

The Chinese developed an imperial examination system during the Sui dynasty that lasted till last dynasties of China. It was one of the most efficient practice of the imperial system which has helped Chinese dynasties to maintain their rule for centuries.They conducted tough civil service exams to recruit only the best bureaucrats to work for state bureaucracy. This helped the dynasties to have proficient and capable bureaucrats and statesmen who helped in the administration of the rulers.

Ameasuring tape. maybe