如何在显示相应列表项时显示代码块?

How to display code chunk when the corresponding list item is displayed?

在以下 RMarkdown MWE 中:

---
title: "Untitled"
output: 
 beamer_presentation:
   slide_level: 2
---

# Paragraph

## Slide

Hello

>- This is the first item
>- This is the second item

  ```{r}
  a <- 2+2
  ```

我希望在生成的 PDF 文件中显示第二个列表项时显示代码块,而不是在显示第一个列表项时显示代码块。

将代码包含在 > 块中。这行得通,

---
title: "Untitled"
output: 
 beamer_presentation:
   slide_level: 2
---

# Paragraph

## Slide

Hello

>- This is the first item

>- This is the second item
> 
>   ```{r}
>   a <- 2+2
>   ```