Some very useful abbreviations and their full origins

Here's a link to an extremely interesting site on writing. This time, I bring you 20 abbreviated forms, their meaning, their origins and their place in normal modern formal writing.

http://www.dailywritingtips.com/20-clipped-forms-and-their-place-if-any-in-formal-writing/

Regards,
Alex Mierez Revilla.