在列表中的项目上方插入小线而不添加额外空间

Question

我想在列表的某些项目之间插入一条小线，以便它看起来大致如下：

(1) This is the first line

(2) This is the second line
    --------
(3) This is the last line

这是我目前所拥有的：

\documentclass{article}
\usepackage{enumitem}
\begin{document}

\begin{enumerate}[label=(\arabic*)]
    \item This is the first item
    \item This is the second item
    \\ \rule{2cm}{1pt}
    \item This is the last item
\end{enumerate}

\end{document}

但是，这会导致规则被放置在其自己的行上，从而在列表中创建一个巨大的空间：

我怎样才能画出这样的线，而没有多余的空间，也不结束枚举环境？

此外，这部分不是必需的，但是是否可以使线的左侧与列表中项目标签的左侧对齐？例如：

(1) this is the first line
------------
(2) this is the last line

Answer 1

当我这样做时，我希望由于该行而增加一些空间，但不会像在常规高度行上那样增加空间。另外，我希望该行从列表的左侧开始。

例如：

\documentclass{article}
\usepackage{enumitem,expdlist}
\newlist{inferenum}{enumerate}{10}
\setlist[inferenum]{%
  label={\arabic*.},
  ref={\arabic*},
  itemsep=.25\baselineskip,
  parsep=0pt,
  labelindent=\parindent,
  leftmargin=*,
  widest={99},
  align=left,
  before*={%
    \pagebreak[3]%
    \renewcommand{\listpartsep}{-.5\baselineskip}%
    \renewcommand{\inferline}{%
      \listpart{%
        \hspace{\trythis}\rule{25mm}{0.5pt}%
      }%
    }%
  },
}
\let\sent\item
\newlength{\trythis}
\setlength{\trythis}{\parindent}
\newcommand{\inferline}{}
\begin{document}
\begin{inferenum}
  \sent This is given as one thing.
  \sent This is taken to mean another.
  \inferline
  \sent Finally, the upshot is the result.
\end{inferenum}
\end{document}

给出

根据你的需求，你可以这样写，例如，

\documentclass{article}
\usepackage{enumitem,expdlist}
\newlist{inferenum}{enumerate}{10}
\setlist[inferenum]{%
  label={\arabic*.},
  ref={\arabic*},
  itemsep=.25\baselineskip,
  parsep=0pt,
  labelindent=\parindent,
  leftmargin=*,
  widest={99},
  align=left,
  before*={%
    \pagebreak[3]%
    \renewcommand{\listpartsep}{-\topsep}%
    \renewcommand{\inferline}{%
      \listpart{%
        \hspace{2\labelindent}\rule{25mm}{0.5pt}%
      }%
    }%
  },
}
\let\sent\item
\newcommand{\inferline}{}
\begin{document}
\begin{inferenum}
  \sent This is given as one thing.
  \sent This is taken to mean another.
  \inferline
  \sent Finally, the upshot is the result.
\end{inferenum}
\end{document}

Answer 2

像这样？我还\sepitem为上面带有分隔线的项目定义了一个命令：

\documentclass{article}

\usepackage{enumitem}
\newcommand\sepitem{\item\raisebox{2.8ex}[0pt]{\rlap{\rule{2cm}{0.8pt}}}}

 \begin{document}

\begin{enumerate}[label=(\arabic*)]
\item This is the first item
\item This is the second item
\item\raisebox{2.8ex}[0pt]{\rlap{\rule{2cm}{1pt}}}%
 This is the last but one item
\sepitem This is the last item
\end{enumerate}

\end{document}