Tags are very common in spoken English, and have many functions. One of the common functions is to start a conversation or help keep it going. The two basic rules about tag questions are:1  If the statement is negative, the tag must be positive.ags are very common in spoken English, and have many functions. One of the common functions is to start a conversation or help keep it going. The two basic rules about tag questions are:
The average cost for a community to fluoridate its water is estimated to range from approximately $0.50 a year per person in large communities to approximately $3.00 a year per person in small communities. For most cities, every $1 invested in water fluoridation saves $38 in dental treatment costs.55 âFor most cities, every $1 invested in water fluoridation saves $38 in dental treatment costs.â It can be calculated from these data that the average lifetime cost per person to fluoridate a water system is less than the cost of one dental filling.
1 Fluoride tablets and drops, rinses and toothpastes, are more expensive and less effective than the fluoridation of drinking water. 2  3. 3  Every dollar spent on fluoridation on average saves $38 in avoided dental bills. 4  Over a lifetime the cost of fluoridation is typically less than the cost of one dental filling. 5. 2  A study found that the annual savings associated with fluoridation in Colorado was $148.9 million (credible range, $115.1 million to $187.2 million) in 2003, or an average of $60.78 per person (credible range, $46.97 to $76.41). 6.