注释掉一些行，但保留它们在文档中包含时会创建的间距

Question

考虑：

\documentclass{article} 
\usepackage{comment}
% \includecomment{answer} %show answers
\excludecomment{answer} % do not show answers

\begin{document}

Question 1: How many hours are in a day?

\begin{answer}

There are 24 hours in a day.

\end{answer}

Question 2: How many minutes are in an hour?

\begin{answer}

There are 60 minutes in an hour.

\end{answer}

\end{document}

取决于以下两条线中的哪一条：

\includecomment{answer} %show answers
\excludecomment{answer} % do not show answers

是文档的一部分并且被注释掉，答案行将显示或不显示。

如果处于活动状态，是否可以\excludecomment{answer}保留问题行之间的间距？间距量应为问题行之间的间距是否包括答案。截至目前，当答案被排除时，问题之间没有间距。

这个想法是创建在问题之间留有空格的文档，以便学生可以在课堂上用笔/铅笔填写空格，而我保留排版的答案。

如果comment包装无法实现这一点，那么任何其他保留间距的替代方法也是有用的。

Answer 1

快速而粗略（假设您不想在文档中使用花哨的颜色）。

\documentclass{article}
\usepackage{xcolor,graphicx}
\newcommand{\answer}{\color{white}}
\newcommand{\question}{\color{black}}
\begin{document}

\question

Question 1: How many hours are in a day?

\answer

There are 24 hours in a day.

\question

Question 2: How many minutes are in an hour?

\answer

There are 60 minutes in an hour.
\end{document}

Answer 2

这将使用 lrbox 和 minipage 创建一个新的答案环境。

\documentclass{article}
\usepackage{showframe}% alignment tool

\newif\ifshowanswers
\newsavebox{\answerbox}
\newenvironment{answer}{\par%\noindent
  \begin{lrbox}{\answerbox}%
  \begin{minipage}[t]{\dimexpr \linewidth-\parindent}}% body
{\end{minipage}\end{lrbox}%
  \ifshowanswers
    \usebox\answerbox\par
  \else
    \vskip\ht\answerbox
    \vskip\dp\answerbox
  \fi}
  
\showanswerstrue
%\showanswersfalse

\begin{document}

Question 1: How many hours are in a day?

\begin{answer}

There are 24 hours in a day.

\end{answer}

Question 2: How many minutes are in an hour?

\begin{answer}

There are 60 minutes in an hour.

\end{answer}

\end{document}