Can I selectively ignore the thesaurus file in a SQL Server full-text query?

Question

Can I choose to ignore the tsENU.xml thesaurus file in a full-text query in SQL Server 2005?

IF @x = 0 THEN
    BEGIN
        SELECT FROM FREETEXTTABLE(use subtitutions and expansions in thesuarus)
    END
ELSE
    BEGIN
        SELECT FROM FREETEXTTABLE(just match based on the exact query terms, no thesuaurs)
    END