When you burn, you must cool the area under cold water.
You must eat fruit and drink water after sport.
You must keep the volume down when you use headphones.
You must brush our teeth carefully three times a day.
You mustn't spend long periods of time looking bright screens specially in dark place.
You mustn't eat sweets when you have stomach-ache.
You mustn't burn your tongue with very hot food or drink because it can cause pain and swelling.
You mustn't smoking. It can damage the taste buds.