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 Water Authority is incorporating seawater desalination into its diversified water supply portfolio. This new, drought-proof supply will reduce the regionâs dependence on water from the Colorado River and the Bay-Delta that is vulnerable to droughts, natural disasters and regulatory restrictions.he additional costs for improvements to the Water Authorityâs system to integrate the new supply bring the total cost of desalinated seawater to $2,014 to $2,257 per acre-foot in 2012 dollars, again depending on how much desalinated water is purchased each year.