Gray code appears and explains how to write it.

I recently went to a fever clinic in a medical institution in China.

If the health code turns gray, it may be because:

1. I recently went to the fever clinic of a Chinese medicine medical institution. At this point, the health code system will become unmarked, that is, the health code will turn gray.

2. The health code turns gray, or it may be because people who don't play the health code for a long time can do a nucleic acid test if necessary as long as they finish playing the health code in time, and the negative result will turn into a green code.

3. When the health code is opened for the first time, the mobile phone number is displayed in gray.

4. In some areas, because the nucleic acid test was not carried out in accordance with the regulations for 48 hours, the health code was displayed in gray. Gray code is used to remind the public that nucleic acid sampling is needed. Just write an explanation according to the specific reasons.