Newtheoremstyle 头部与 tabularx 顶部对齐

Question

以下是一个例子：

\documentclass[12pt]{report}
\usepackage{amsmath, amssymb, amsthm}

\usepackage{tikz}
\usetikzlibrary{shadows}
\newcommand*\squared[1]{\tikz[baseline=(char.base)]{\node[shape=rectangle, draw, inner color = white, drop shadow = {opaque, black}, inner sep=3pt, text justified] (char) {#1};}}

\newtheoremstyle{exercise}
  {\topsep}
  {\topsep}
  {\hangindent=2em}
  {}
  {}
  {}
  {.8em}
  {\squared{\thmnumber{#2}}}

\theoremstyle{exercise}
\newtheorem{exercise}{}

\renewcommand{\arraystretch}{1.75}
\usepackage{tabularx}

\begin{document}

\begin{exercise}
    \begin{tabularx}{\textwidth}{r @{\hskip .4em} X}
        a) & This is a test. \\
        b) & This is a long test. \\
        c) & This is a very long test.
    \end{tabularx}
\end{exercise}

\end{document}

我想要的是练习的编号与顶部表格（问题 a））而不是与中间的 tabularx。

Answer 1

使用t（顶部对齐）作为可选参数tabularx：

\documentclass[12pt]{report}
\usepackage{amsmath, amssymb, amsthm}

\usepackage{tikz}
\usetikzlibrary{shadows}
\newcommand*\squared[1]{\tikz[baseline=(char.base)]{\node[shape=rectangle, draw, inner color = white, drop shadow = {opaque, black}, inner sep=3pt, text justified] (char) {#1};}}

\newtheoremstyle{exercise}
  {\topsep}
  {\topsep}
  {\hangindent=2em}
  {}
  {}
  {}
  {.8em}
  {\squared{\thmnumber{#2}}}

\theoremstyle{exercise}
\newtheorem{exercise}{}

\renewcommand{\arraystretch}{1.75}
\usepackage{tabularx}

\begin{document}

\begin{exercise}
    \begin{tabularx}{\textwidth}[t]{r @{\hskip .4em} X}
        a) & This is a test. \\
        b) & This is a long test. \\
        c) & This is a very long test.
    \end{tabularx}
\end{exercise}

\end{document}

与问题无关，但为了防止过满，\hbox您需要减少宽度tabularx。