循環

to cycle / to circulate / circle / loop

to follow / to adhere to / to abide by

surname Huan

ring / hoop / loop / (chain) link / classifier for scores in archery etc / to surround / to encircle / to hem in

circulatory system

vicious circle

round-robin tournament

recurring decimal

cyclical / cyclic / circulatory / recurrent / recursive / cyclicity

recurring section of a rational decimal

circular argument / logical error consisting of begging the question / Latin: petitio principii

citric acid cycle / Krebs cycle / tricarboxylic acid cycle

fuel cycle

virtuous cycle (i.e. positive feedback loop)

blood circulation

Rankine cycle (engineering)

coronary circulation

closed-circuit rebreather scuba (diving)

recycle / to use in cyclic order