如何使用pdf_document

Question

如何获得此结果，其中源代码和输出都使用pdf_document在R markdown中用一行换行。

我的Yaml配置如下：

---
title: 'Applied Econometrics using R'
subtitle: 'Federal University of Paraiba'
author: 'Alexandre Loures'
date: "`r Sys.Date()`"
documentclass: book
bibliography: [econometrics.bib]
biblio-style: apalike
link-citations: yes
colorlinks: yes
lot: yes
lof: yes
output:
 html_document:
  theme: united
 pdf_document:
  highlight: tango
description: "A book example for a Chapman & Hall book."
github-repo: yihui/bookdown-crc
graphics: yes
#cover-image: images/cover.jpg
---