Mrs. IS the abbreviation - the word is mistress.
Decibel is short dB.
Blvd.
Either "abbr." or "abbrev."
Its an abbriveation, if that's what you mean.
Coming from the latin words id est, meaning "in other words"
And RO unit is a water purifier and RO is the abbriveation of reverse osmosis. http://science.howstuffworks.com/reverse-osmosis.htm
L for liters, ml for milliliters, cc for cubic centimeters, gal for gallon, pt for pint. There are many abbreviations for the different units of volume.
You would use the word "your" when writing about something that belongs or is conected to a person you are writing to. For example... I received your letter today. Or... What is your brother's name? The word "your" should not be confused with the abbrievation "You're," which is a contraction of the phrase "You are."