There is no strict standard to distinguish selenium-enriched tea before and after rain, which is generally the dividing line before and after Qingming. Most of the Se-enriched teas before the Qingming Festival were green buds, with less mitosis and greater activity of mineral elements, especially the anticancer star Se. After being made into tea, it is more conducive to the absorption of cancer patients, can inhibit the spread of cancer cells to a certain extent, and is fragrant and delicious, refreshing, and is the best in tea, but the price is relatively expensive. After the Qingming Festival, selenium-enriched tea grew because of the rising temperature. Minerals contained in tea buds are gradually absorbed by leaves, cell mitosis increases, and mineral activity is relatively small. Although the fragrance is soaked in the nose, the activity of its anticancer components is relatively small, and its self-heating property is not better than that of tea before rain. Moreover, its bubble line is messy and its appearance is not very good, but the selenium content is not much different, its nutritional value is still very high, its price is relatively cheap and its cost performance is good. With the increase of leaves, its anti-cancer effect gradually becomes smaller. As far as I know, the selenium-enriched tea produced in Gu Huan Town, Ziyang County is located in the upper reaches of the Han River, in a natural selenium mine. Nourished by the river all the year round, the tea leaves are green and fragrant, and contain a large amount of selenium, which is the best in health care green tea. I hope I can help you.