Antigen kits that have been left in for a long time and turned into two bars are considered to be the result of expired kits, or they may be the result of being left in for too long, beyond the observation time limit. If the patient observes two bars about ten minutes after the test, medical attention is required. If the patient’s antigen kit has not been unpacked and has been left for a long time, the phenomenon of two bars may be caused by the antigen kit being left for too long, exceeding the preservation time, and the antigen kit has expired, which is a normal phenomenon. If the patient is in use after placing time too long after the phenomenon of two bars, may be the patient in the test after placing time is too long, more than ten minutes, has exceeded the normal observation time caused by the phenomenon, also belongs to the normal phenomenon. In addition, if the patient has two bars within ten minutes after the test, the patient may be infected with the virus, the patient should go to the hospital in time for further examination to avoid misdiagnosis. When two bars appear after the antigen kit has been placed for a long time, it may be a normal phenomenon. If two bars appear within a short period of time, the patient needs to go to the hospital in time.