abbrev
base64
benchmark
bigdecimal
bigdecimal-math
cgi
coverage
csv
date
dbm
digest
erb
fiber
fileutils
find
forwardable
io-console
ipaddr
json
logger
monitor
mutex_m
net-http
nkf
objspace
openssl
optparse
pathname
prettyprint
prime
pstore
pty
resolv
rubygems
securerandom
set
shellwords
singleton
socket
strscan
tempfile
time
timeout
tmpdir
tsort
uri
yaml
zlib