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.
The addition of fluoride to a drinking water supply is generally governed by the Australian Drinking Water Guidelines. The Guidelines recommend a health-related guideline value (maximum concentration) of 1.5 mg/L for fluoride, which mirrors the World Health Organisation Guidelines for Drinking Water Quality 2006.uidance on the concentration of fluoride has been present in the Guidelines since 1983. Like other countries with water fluoridation programs, Australia has organised anti-fluoride groups that contest the health benefits of fluoride.