词汇	an extinct volcano
释义	an extinct volcano 死火山
随便看	operator control panel operator control panelOCP operator control station operator control system operator control system or section operator control table operator data register operator-defined occurrence operator-defining occurrence operator delay operator delete operator dial operator dialing working operator dialling working operator difference table operator differential equation operator-differential equation operator display operator display terminal operator display terminal protocol operator-distal operator distance dialing operator distribution operator document Operator does not go backwards