kuing

用 \subset `\subset` 和 \supset `\supset` 来组合 真机智

试试如果是 KaTeX 渲染的话会咋样
\[\subset\kern{-2.3pt}\supset\kern{-16.8pt}\iint\limits_{\,\large\Sigma}\]\[{\large\subset}\kern{-2.1pt}{\large\supset}\kern{-17.4pt}\iint\limits_{\,\large\Sigma}\]\[\bigcirc\kern{-13.5pt}\int\kern{-8.0pt}\int\limits_{\large\Sigma}\]\[{\large{\bigcirc}}\kern{-15pt}\int\kern{-7pt}\int\limits_{\large\Sigma\,\,}\]

我也来试试：
\[
A\mathop{}\!\!\rlap{\mkern4mu\subset\mkern-4mu\supset}\iint_AA
\]\[A\mathop{}\!\!\rlap{$\mkern4mu\subset\mkern-4mu\supset$}\int\mkern-14mu\int_AA\]KaTeX 的 rlap 竟然会出问题（在真 LaTeX 中都 OK）……
\[A\mathop{}\!\!\mathrlap{\mkern4mu\subset\mkern-4mu\supset}\int\mkern-14mu\int_AA\]mathrlap 也一样……