abcdefgijklmnopqrstuvwxyz‾ \overline {abcdefgijklmnopqrstuvwxyz}abcdefgijklmnopqrstuvwxyz
$$ \overline {abcdefgijklmnopqrstuvwxyz}$$
对应的下划线为\underline
\underline
abcdefgijklmnopqrstuvwxyz‾ \overline {abcdefgijklmnopqrstuvwxyz}abcdefgijklmnopqrstuvwxyz
$$ \overline {abcdefgijklmnopqrstuvwxyz}$$
对应的下划线为\underline
\underline