There are many ways to say the same thing. Now…. when planning how to ask for something or make a request, we have to consider different factors like who the receiver of our message is, what we really want to get from our message, and many other things…. Check this out:
Gimme the salt! or Would you please pass me the salt?
Same idea, same objective, but probably different context and/or different addressee (person recieving the message)
Here you have some links to a few complete and good documents to learn or revise this topic. I hope you find them useful:
– great ppt with a very complete view and examples about formaliy vs. colloquial English
– This is another great ppt, this time focussing on Spoken English, it includes interesting examples – two videos of Obama exemplifying both levels of formality
– Written English and levels of formality
For advanced learners:
Try these exercises to see how well you can use formal and informal language. Then watch our video on how to create a formal tone in letters.
Try putting your skills to the test with these two quizzes.
INDEPENDENT LEARNING // I'm working on another site now. Take a look at strategiclearnersofenglish.wordpress.com 
These are all great tools! I find that I’m very big on first impressions and I always have to speak good English when I first meet somebody. However, I can feel myself slowly regressing into my colloquialism even though I know that some of these people constantly speak well. It’s like I have to let them know I am capable of speaking well before I allow myself to become more comfortable with my speech.
It’s the same as doing a presentation or speech. Whenever I do those, I speak very well and many teachers have commented that I speak like a totally different person during normal lessons. I guess I think that it’s ok not to speak good English at times but I have to remember to use good English when it matters. It’s not a very good habit but it works for me 🙂