{abcd}{abcd}{abcd}{abcd} \displaystyle {\displaystyle{a\over b}\brace \displaystyle{c\over d}} \textstyle {\displaystyle{a\over b}\brace \displaystyle{c\over d}} \scriptstyle {\displaystyle{a\over b}\brace \displaystyle{c\over d}} \scriptscriptstyle {\displaystyle{a\over b}\brace \displaystyle{c\over d}}