system of taxation system of the body system of the brain system of the company system of the country system of the european system of the future system of the heart system of the human system of the republic system of the united nations system of the united states system of the world system of things system of thought system of trade system of training system of tunnels system of ukraine system of units system of universal system of value added system of values system of vocational system of voting system of water system of weights system of work system of writing system offer system offers system offline system oil system on a chip system on board system on chip system on earth system on social system on the market system once system one system online system only system open system opens system operating system operation system operational system operations system operator system operators system optimization system option system optional system options system or application system or component system or network system organ system organ class system organization system organizations system other system out there system output system overall system overload system overview system owner system package system page system parameter system parameters system part system partition system partner system partners system parts system password system performance system performed system performs system permits system placed system places system plan system planning system platform system play system plays system plays an important system please system policy system possible system power system power supply system preferences system presented system presents