Most often, to address a particular audience, a technical communicator must consider what qualities make a text useful (capable of supporting a meaningful task) and usable (capable of being used in service of that task).
大多数情况下，为了满足某个特定用户的需求，技术传播从业者必须考虑哪些特征会使文档有用（能够支持某个任务）并且可用（以服务于该任务的方式使用）。