Everything about the Language - English

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English - Vocabulary ,Grammar etc....:

Learning English @ BBC

Utminers
Lear English
Ego4u
English Test
English Grammar Secrets
English Hilfen
English Page
Using English
Word English
Ecenglish
Eng 2tion
CSK English Training
Free English Now
Grammarly
Learn English
Check Grammar

Test your English here:
Ego4u cram-up
Eng Test.net

Idioms:
Using English Idioms

Phonetic Alphabet:
Antimoon
Pronunciation Page

US Slang:
Ur Dic American Slang

Useful External Links:
Neutral Accent
PH School
My Pearson Training
Rachels English

Take an Online Test @ Ordniate a.k.a Versant