a384147848 install.packages("MASS") Warning: 无法在貯藏處https://mirrors.eliteu.cn/CRAN/src/contrib中读写索引: 无法打开URL'https://mirrors.eliteu.cn/CRAN/src/contrib/PACKAGES' Warning message: package ‘MASS’ is not available (for R version 3.5.1)
tctcab a384147848 因为国内SB的GFW的问题，很多资源连接都有问题。换镜像试试， 比如 install.packages('RMySQL', repos='http://cran.us.r-project.org') 参考https://stackoverflow.com/questions/11488174/how-to-select-a-cran-mirror-in-r
