![Beamer:使用 itemize/alert 一次更改一行文本的颜色](https://linux22.com/image/348310/Beamer%EF%BC%9A%E4%BD%BF%E7%94%A8%20itemize%2Falert%20%E4%B8%80%E6%AC%A1%E6%9B%B4%E6%94%B9%E4%B8%80%E8%A1%8C%E6%96%87%E6%9C%AC%E7%9A%84%E9%A2%9C%E8%89%B2.png)
我想逐行更改逐项列表中文本的颜色。这是我使用的代码:
\documentclass{beamer}
\mode<presentation>
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{array}
\usepackage{graphicx}
\begin{document}
\begin{frame}[t]
\begin{theorem}
$\sqrt{2}$ is irrational.
\end{theorem}
\begin{block}
\begin{proof}
The proof is by contradiction.\pause
\begin{itemize}
\item \alert {item 1} \pause
\item \alert {item 2} \pause
\item \alert {item 3} \pause {Contradiction.}
\end{itemize}
\end{proof}
\end{block}
\end{frame}
\end{document}
这样会突出显示每一行,但之后会保持突出显示状态。如何让文本恢复到原始颜色,以便只突出显示有问题的行?