【计】 loop maintenance operation system
cycle; recur; circle; rotate; circulation; repetition; revolution
【计】 DO-loop; for-loop; loop; unwinding
【化】 recirculate
【医】 circuIation; cycle
【经】 cycle; revolving; rotation
preserve; defend; maintain; safeguard; stick up for; vindicate
【计】 maintenance; servicing
【化】 maintaining
【计】 operating system; OS
【化】 operating system