$$
\displaystyle \dbinom{\displaystyle{a\over b}}{\displaystyle{c\over d}}
\textstyle \dbinom{\displaystyle{a\over b}}{\displaystyle{c\over d}}
\scriptstyle \dbinom{\displaystyle{a\over b}}{\displaystyle{c\over d}}
\scriptscriptstyle \dbinom{\displaystyle{a\over b}}{\displaystyle{c\over d}}
$$
