Почему я получаю ошибку при установке JSON gem в Ubuntu?

Используя Ubuntu, когда я запускаю "bundle install", чтобы настроить среду Rails, она выдает ошибку во время установки gem JSON:

Installing json (1.7.3) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

/usr/bin/ruby1.9.1 extconf.rb 
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf (LoadError)
    from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from extconf.rb:1:in `<main>'

Gem files will remain installed in /home/danny/.bundler/tmp/2040/gems/json-1.7.3 for inspection.
Results logged to /home/danny/.bundler/tmp/2040/gems/json-1.7.3/ext/json/ext/parser/gem_make.out
An error occured while installing json (1.7.3), and Bundler cannot continue.
Make sure that `gem install json -v '1.7.3'` succeeds before bundling.

Когда я пытаюсь установить только JSON 1.7.3, это также дает мне ошибку:

Building native extensions.  This could take a while...
ERROR:  Error installing json:
    ERROR: Failed to build gem native extension.

/usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf (LoadError)
    from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from extconf.rb:1:in `<main>'

Gem files will remain installed in /var/lib/gems/1.9.1/gems/json-1.7.3 for inspection.
Results logged to /var/lib/gems/1.9.1/gems/json-1.7.3/ext/json/ext/parser/gem_make.out

Я установил RVM и запускаю Ruby 1.9.3; Почему он не может установить JSON-камень?

Ответ 1