> For the complete documentation index, see [llms.txt](https://overleaf-pro.ayaka.space/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://overleaf-pro.ayaka.space/latex/zh-cn/latex-cuo-wu/13-latex-error-can-be-used-only-in-preamble.md).

# LaTeX 错误：只能在导言区使用

当你将某个宏包或类包含在文档正文中，而不是放在导言区中时，就会出现此错误。文档的导言区由所有在以下内容之前写入的内容组成 **`\begin{document}`**。在导言区中，你定义所写文档的类型、语言以及其他几个元素。例如，一个普通的文档导言区会像这样：

```latex
\documentclass[12pt, letterpaper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}

\title{第一份文档}
\author{Hubert Farnsworth \thanks{由 ShareLaTeX 团队资助}}
\date{2014年2月}
```

如果你写 **`\usepackage{...}`** 在文档正文中（在 **`\begin{document}`**）而不是在导言区中，你就会生成下面显示的错误信息。

main.tex，第7行

LaTeX 错误：只能在导言区中使用。

参阅 LaTeX 手册或 LaTeX Companion 以获得解释。键入 H 可立即获得帮助。... l.4 \usepackage {amsmath} 你的命令已被忽略。键入 I 可将其替换为另一个命令，或在不使用它的情况下继续。\[1

要修复此错误，请确保所有 **`\usepackage{...}`** 命令，以及 **`\documentclass[...]{...}`**，都写在 **`\begin{document}`**。若要了解更多关于如何在 LaTeX 中组织文档的信息，请查看我们的 [文档](/latex/zh-cn/latex-ji-chu/01-learn-latex-in-30-minutes.md).


---

# Agent Instructions
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## Querying This Documentation
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Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

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GET https://overleaf-pro.ayaka.space/latex/zh-cn/latex-cuo-wu/13-latex-error-can-be-used-only-in-preamble.md?ask=<question>&goal=<endgoal>
```

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