lap测试

$\nearrow$
$\searrow$
$\rlap{\nearrow}\searrow$
$\llap{\nearrow}\searrow$
$\clap{\nearrow}\searrow$
$\rlap XX$
$\llap XX$
$\rlap{\nearrow}\nearrow$
$\rlap{\nearrow}{\nearrow}$

$\rlap{\nearrow}{\searrow}$

OK
$\newcommand\jcjt{\rlap{\nearrow}{\searrow}}$
$\newcommand\rto\rightarrow$
$\newcommand\lto\leftarrow$
$\newcommand\uto\uparrow$
$\newcommand\dto\downarrow$
$\newcommand\ruto\nearrow$
$\newcommand\rdto\searrow$
$\newcommand\luto\nwarrow$
$\newcommand\ldto\swarrow$

\[\Large
\begin{array}{ccc}
A & \!\!\!\rto & \!\!\!B\\
\dto & \!\!\!\jcjt & \!\!\!\dto\\
C & \!\!\!\lto & \!\!\!D
\end{array}
\]