What is the "three listening and four smelling" mentioned in the patrol of the property order department?

Be gentle (speak softly when walking); Second, look (carefully look at the inspected place, recognize the truth, and observe the line of sight with your eyes); Third, listen (listen for abnormal sounds in your ears and listen carefully for abnormal sounds along the way); Four smells (smell whether there is abnormal smell with your nose, and find the source of the smell in time); Five touches (touch whether each door lock is closed normally by hand, and deal with various problems in time according to relevant regulations)

These are all summarized by enterprises themselves, and there is no standard answer at all.