OPOSSUMS ARE MARSUPIALS. If you open just about any field guide to North American mammals, the opossum will probably be the very first of the 380 or so mammal species described. That's because opossums are our only marsupial, and marsupials are considered very ancient forms of mammals.
operator - an agent that operates some apparatus or machine; the operator of the switchboard. manipulator. causal agency, causal agent, cause - any entity that produces an effect or is responsible for events or results. company operator - an operator who works for a company. driver - the operator of a motor vehicle.
A refinery operator is a person who works in a refinery, which is a facility that converts raw materials into useful products. The term is most often applied to people who work in the oil industry, though it can have other applications. If you want to become a refinery operator, you will first need to determine what area of refining you want to get into.