Typical responsibilities include process guidance, process review, product audit, process improvement and process measurement. As a policeman, QA needs to find and report the problems of the project in time, selectively participate in the technical review of the project, and regularly audit and review the work products and processes of the project based on business processes. As a teacher, QA assists the project manager to make the project plan, including the process of cutting out the project definition according to the standard process in the quality system, helping the project to estimate and set the quality objectives. Train project members on procedures and specifications, and guide them in the process. As a doctor, QA can undertake the collection, statistics and analysis of measurement data, diagnose the project process, help analyze the reasons and write prescriptions.