Q:

How make lyx recognize single alphabetic a, b, c ....as mathematical symbols

I have to describe a mathematical model in words like a story. In this description I explain the variables and parameters, they are mainly alphabetic like d,B, C, R, r and etc. My question is how I make Lyx understand that these letters are mathematical symbols.  
Thanks for your patience.

A:

The keyboard shortcut for inline math is Ctrl + M, and using that might be quicker than clicking the symbol on the toolbar. 
It might also be possible to do it all in one go with advanced find and replace, as you can use math mode in the replace text. So use Edit -> Find & Replace (Advanced), keyboard shortcut Ctrl + Shift + F. Type e.g. B in the search field, and in the replace field hit Ctrl + M and then type B. Enable "Whole words", and hit Replace all (or just Replace, if you want to try one at a time).  
In the future I'd probably write the text in LyX, and use math mode when needed.
Another method would be to write dollar signs around the variables in Word, e.g. $B$, and when you paste the text in LyX, use Edit -> Paste special -> Paste from LaTeX. The LaTeX code for math mode ($ ... $) will be interpreted properly.

