$\frac{B}{B}$

$\frac{B}{}$

$D$

$\frac{\frac{A}{A}}{\frac{A}{A}}$

$\frac{\frac{D}{D}}{\frac{D}{D}}$

$\frac{\frac{B}{B}}{\frac{B}{B}}$

$\frac{B}{B}$

$\frac{\frac{C}{C}}{\frac{C}{C}}$

$\frac{\frac{D}{D}}{\frac{D}{D}}$