Self-testing breath is very simple, you can try the following: first, the left and right palms together and collected into a closed bowl, wrapped around the mouth and nose, and then breathe into the gathered palms, you can smell their mouth; second, you can use a cotton swab to wipe in the mouth in many places, and then take out the smell, you can also find out if you have obvious bad breath; third, you can ask a close friend to help, close Speaking to a friend, you can ask the friend to help find out if you have bad breath. Generally bad breath is caused by pathological reasons, short-term can consider quick-acting and non-damaging methods to freshen breath, such as chewing sugar-free gum, putting a few pieces of tea in the mouth to chew, using oral freshening sprays, etc.