Problem1: R安裝不了包，以及出現了類似的報錯：
cannot open URL 'https://cran.rstudio.com/src/contrib/PACKAGES'
cannot open URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/PACKAGES'
R安裝不了包，出現了類似的報錯：
Warning: unable to access index for repository https://cran.rstudio.com/src/contrib:
cannot open URL 'https://cran.rstudio.com/src/contrib/PACKAGES'
Solve1:
Problem2: R安裝時注意項
安裝鏡像的選擇——CRDN——mirrors——CHINA——清華鏡像
Problem3: Rstudio打開後中文亂碼，保存和打開的注意項
