运行了一下 rvm list known，结果：

# MRI Rubies
[ruby-]1.8.6[-p420]
[ruby-]1.8.7[-head] # security released on head
[ruby-]1.9.1[-p431]
[ruby-]1.9.2[-p330]
[ruby-]1.9.3[-p551]
[ruby-]2.0.0[-p643]
[ruby-]2.1.4
[ruby-]2.1[.5]
[ruby-]2.2[.1]
[ruby-]2.2-head
ruby-head

我很着急