Use the software with care as some of them has incorrect answers to their exercises. This is a web page that has an impressive and extensive collection of On-Line English Lesson Sites. Site has tons of examples on idiomatic and colloquial American English complete with examples and explanations in Chinese. Interesting things for ESL students This site has all kinds of little exercises for introductory level English Lessons . An interesting cultural exchange and language site run by two interesting young people.
Site is currently under construction.
There is also a slang page that has a good collection of English slangs along with their Chinese equivalences and examples of usage. Check in on them once in awhile to see what's brewing. English Idioms I recommend this site highly. It has questions, answers, explanations and examples on some common North American idiomatic expressions. Knowing these expressions should greatly facilitate your communication with a North American English Speaker.