结合枚举和对齐在定理环境中有效，但在定理环境之外无效

Question

我之前使用的是 MWE 1（运行良好），但现在我想摆脱定理环境（MWE 2）。但是，这不起作用，我收到以下错误。有什么想法可以让 MWE 2 正常工作吗？

---

错误

! LaTeX Error: Something's wrong--perhaps a missing \item

See the LaTeX manual or LaTeX Companion for explanation.
Type H <return>  for immediate help.
 ...

1.14      \end{align}
                     %

---

微波能量吸收 1

\documentclass{article}
\usepackage{amsmath,amsthm}
\newtheorem{theorem}{Theorem}[section]

\begin{document}%

\begin{theorem}%
\begin{enumerate}%
    \begin{align}%
    \intertext{\item Condition $A$}
    a &= b
    \intertext{\item Condition $B$}
    c &= d
    \end{align}%
\end{enumerate}%
\end{theorem}%

\end{document}%

微波辐射计 2

\documentclass{article}
\usepackage{amsmath,amsthm}
\newtheorem{theorem}{Theorem}[section]

\begin{document}%

\begin{enumerate}%
    \begin{align}%
    \intertext{\item Condition $A$}
    a &= b
    \intertext{\item Condition $B$}
    c &= d
    \end{align}%
\end{enumerate}%

\end{document}%

Answer 1

我不知道定理的最佳实践，但正常情况下，你至少需要一个\item数学模式之外的定理。请看我的第二个示例，这是正确的语法。

% arara: pdflatex

\documentclass{article}
\usepackage{mathtools,amsthm}
\newtheorem{theorem}{Theorem}[section]

\begin{document}    
\begin{theorem}
    \begin{enumerate}
        \begin{align}
            \intertext{\item Condition $A$}
            a &= b
            \intertext{\item Condition $B$}
            c &= d
        \end{align}
    \end{enumerate}
\end{theorem}       
\begin{enumerate}
    \item Condition $A$ % move this out from the align
    \begin{align}           
        a &= b
        \intertext{\item Condition $B$}
        c &= d
    \end{align}
\end{enumerate}
\end{document}

---

题外话：\shortintertext{}在这里看起来会更好。

就我个人而言，我会这样做：

% arara: pdflatex

\documentclass{article}
\usepackage{mathtools,amsthm}
\newtheorem{theorem}{Theorem}[section]
\usepackage{enumitem}
\usepackage{blindtext}

\begin{document}
    \blindtext  
\begin{theorem}\leavevmode
    \begin{enumerate}[labelindent=0pt,labelwidth=\widthof{Condition \textit{A}},label=Condition \Alph*,itemindent=4em,leftmargin=!]
        \item
        \begin{align}
            a &= b
            \shortintertext{\item\mbox}
            c &= d
        \end{align}
    \end{enumerate}
\end{theorem}       
\begin{enumerate}[labelindent=0pt,labelwidth=\widthof{Condition \textit{A}},label=Condition \Alph*,itemindent=4em,leftmargin=!]
    \item
    \begin{align}           
        a &= b
        \shortintertext{\item\mbox}
        c &= d
    \end{align}
\end{enumerate}
\end{document}