There are several synonyms that can be used in place of the phrase "did a job." Some options might include "completed a task," "performed a duty," "executed a project," or "fulfilled an assignment." All of these phrases imply that some sort of work has been accomplished, but they may be more specific or nuanced in their meaning. For example, "executed a project" may suggest a more formal, structured process with specific deliverables, while "performed a duty" might be more general and encompass a wide range of tasks. Ultimately, the choice of synonym will depend on the context and the speaker's intentions in communicating the accomplishment of work.