问在RStudio中Knitr HTML预览失败，尽管render()成功创建了HTML文件

EN

---
title: "Monthly Report"
author: "Kris Shaffer"
date: "February 17, 2017"
output: html_document
---

```{r setup, include=FALSE}

## R Markdown

This is an R Markdown document. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see <http://rmarkdown.rstudio.com>.

When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document. You can embed an R code chunk like this:

```{r cars}

## Including Plots

You can also embed plots, for example:

```{r pressure, echo=FALSE}

Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.