ruby ri工具不生效，提示Nothing known about， 如何解决？

[funnyone]

ruby ri工具不生效，提示Nothing known about， 然后网上找下需要执行gem install rdoc-data，但是还是不行。

D:\books\ruby\my-code\c1>ri String
Nothing known about String

D:\books\ruby\my-code\c1>gem install rdoc-data
ERROR:  Could not find a valid gem 'rdoc-data' (>= 0), here is why:
          Unable to download data from https://rubygems.org/ - Errno::ETIMEDOUT: A connection attempt failed because the connected party did not prope
rly respond after a period of time, or established connection failed because connected host has failed to respond. - connect(2) (https://rubygems.org/
latest_specs.4.8.gz)
ERROR:  Possible alternatives: rdoc-data

[Chary_Gao]

Your ruby version 2.2.3 is not supported, only 1.8.7, 1.9.2, 1.9.3, 2.0.0，你是2.2.3版本吧？！