安装knitr这个包的时候出现了以下问题
<br />
> install.packages("knitr")<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
unable to access index for repository http://cran.rstudio.com/bin/windows/contrib/3.0<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
unable to access index for repository http://www.stats.ox.ac.uk/pub/RWin/bin/windows/contrib/3.0<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
unable to access index for repository http://cran.rstudio.com/bin/windows/contrib/3.0<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
InternetOpenUrl failed: '无法与服务器建立连接'<br />
Warning in install.packages :<br />
unable to access index for repository http://www.stats.ox.ac.uk/pub/RWin/bin/windows/contrib/3.0<br />
Warning in install.packages :<br />
package ‘knitr’ is not available (for R version 3.0.3)<br />
><br />
</p>
这个怎么解决呀？有点郁闷
