两位数的十位数字与个位数字之和为$$12$$，  而数字均为$$0\sim 9$$，故枚举得：  $$93$$，$$84$$，$$75$$，$$66$$，$$57$$，$$48$$，$$39$$共$$7$$个．  故选：$$\text{C}$$． 
\textbf{(2019 Youth Mathematics Olympics, Primary 1, Question \#6)~}  The sum of the ten digits and the single digit is $$12$$, and there are a total of  such two-digit numbers.  十位数字和个位数字相加的和是$$12$$，这样的两位数一共有个． 
  * $$5$$ 
  * $$6$$ 
  * $$7$$ 
  * $$8$$ 