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