ACCESS SQL Adding Multiple Columns If They Don't Exist

I'm trying to add several new columns to a table that already exists in Access 2007 or 2010 with a query. Right now my code looks like this (yes, I'm terribly new to this):

ALTER TABLE AC_PROPERTY

ADD JAB_1 double,

JAB_2 double,

JAB_3 double;

This correctly adds the three columns when none of them already exist, but if any of them exist I get an error message and the query fails to run. I need it to add each columns only if it does not exist. Can anyone please help with what my code should look like to check if each column exists before trying to add it?

NOTE: I would just do 3 queries for each column, but I actually need to add 20+ columns. This is just a simple example of my actual use.

Thanks a billion!