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.
They also offer costs savings annual energy costs. The running costs vary from gas to electric. The average running cost for an electric water heater is $550. The average running costs of a gas water heater is $400. The difference in usage price per year is $150.he average cost for gas water heating units is $850. That will buy you a decent water heater that is rated for 12 years. These, too, can be found for cheaper than that price. You may find a 3 year rated water heater for about $350. Quality units can cost $1,000 to $1,400.