${\displaystyle \underset{O}{O}}{O}_O$ ${\displaystyle \frac{O_O}{O_O}}$ ${\displaystyle \sqrt[O_O]{\underset{O}{O}}\sqrt{\underset{O}{O}}}$ ${\displaystyle {\underset{O}{O}}_{O_O}{\underset{O}{O}}^{O_O}{\underset{O}{O}}_{O_O}^{O_O}{}_{O_O}{}^{O_O}\underset{O}{O}_{O_O}^{O_O}}$ ${\displaystyle \underset{O_O}{\underset{O}{O}}\stackrel{O_O}{\underset{O}{O}}\underset{O_O}{\overset{O_O}{\underset{O}{O}}}}$ $\begin{array}{c}\underset{O}{O}\end{array}{\displaystyle \begin{array}{c}{O}_O\end{array}}$