> install.packages("vcd")
警告: 无法在貯藏處http://ftp.ctex.org/mirrors/CRAN/bin/windows/contrib/3.1中读写索引
警告: 无法在貯藏處http://www.stats.ox.ac.uk/pub/RWin/bin/windows/contrib/3.1中读写索引
错误于.install.winbinary(pkgs = pkgs, lib = lib, contriburl = contriburl,  :
  无法建立临时目录‘C:\DOCUME~1\LIYING~1\LOCALS~1\Temp\RtmpYdY3Td\downloaded_packages’



这是什么原因，如何解决？