To "do duty as" is a phrase used to describe a situation when someone or something is assigned or takes on a particular responsibility or role, often temporarily or as a substitute. It implies that the person or thing serves or fulfills a specific purpose, task, or function, typically in the absence of the usual or designated individual or object. It can also refer to someone or something that performs or functions adequately in a given situation, despite not being the intended or ideal choice.
When someone "does duty as," they are essentially stepping in or assuming a role or duty that is not their primary function or designation. For instance, if a regular teacher is absent, a substitute teacher may "do duty as" the classroom instructor, meaning they will temporarily fulfill the teaching responsibilities. Similarly, if a regular vehicle is unavailable, another vehicle may "do duty as" a replacement for transportation needs.
Furthermore, "doing duty as" can also be used to express a person or thing's ability or capacity to serve a particular function. Even if they are not originally intended for such purposes, they are capable of performing reasonably well in that role. For example, a simple household item like a kitchen knife can "do duty as" a makeshift screwdriver in certain situations, despite not being specifically designed for that purpose.
In summary, "doing duty as" refers to the act of assuming a role, temporarily fulfilling a responsibility, or functioning adequately in a particular capacity, often as a substitute or alternative to the usual option.
