> For the complete documentation index, see [llms.txt](https://ayakaleaf-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://ayakaleaf-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

当你在文档主体中而不是在导言区包含了某个宏包或类时，就会出现此错误。文档的导言区由在此之前写入的所有内容组成。 **`\begin{document}`**。在导言区中，你定义所写文档的类型、语言以及其他一些元素。例如，普通文档的导言区会像这样：

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

\title{First document}
\author{Hubert Farnsworth \thanks{funded by the ShareLaTeX team}}
\date{February 2014}
```

如果你写： **`\usepackage{...}`** 在文档主体中（在……之后） **`\begin{document}`**）而不是在导言区中，你就会产生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。

请参阅 LaTeX 手册或 LaTeX Companion 获取解释。输入 H 可立即获得帮助。... l.4 \usepackage {amsmath} 你的命令已被忽略。输入 I 可将其替换为另一个命令，或继续而不使用它。\[1

要修复此错误，请确保所有 **`\usepackage{...}`** 命令，以及 **`\documentclass[...]{...}`**，都写在……之前 **`\begin{document}`**。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).


---

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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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