摘要：One of the strengths of the R Project is its package
system and its network of archives of packages.
All useRs will be (or at least should be) familiar
with CRAN, the Comprehensive R Archive Network,
which provides access to more than 600 contributed
packages. This wealth of contributed software
is a tribute to the useRs and developeRs who
have written and contributed those packages and
to the CRAN maintainers who have devoted untold
hours of effort to establishing, maintaining and continuously
improving CRAN.
