as ‘lib’ is unspecified，在下载R中的包时出现错误，然后无法加载，虽然已经下下来了，但是无法使用包！
> install.packages("glmnet")
Installing package into ‘C:/Users/ZDY/Documents/R/win-library/3.2’
(as ‘lib’ is unspecified)
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.2/glmnet_2.0-2.zip'
Content type 'application/zip' length 1981055 bytes (1.9 MB)
downloaded 1.9 MB