R markdown挂起，但所有代码块都有效

Question

R markdown卡在第1块上，在下面重复：

---
title: "RMark1"  
author: "df"  
date: "11/19/2017"  
output:  
  html_document:  
    toc: true  
---

```{r setup}
library(dplyr)
library(knitr)
library(rmarkdown)
library(ggplot2)
library(plotly)
library(readr)
knitr::opts_chunk$set(echo = TRUE)
print("loaded libraries")
```  

我在这里缺少什么？