Verbatim string will add the new line character and all the extra spaces as specified in your query. So for your string you will get:
So your string would look like USE Database \r\n space(s) SET TRANSACTION.......
See: String C#
Because verbatim strings preserve new line characters as part of the string text, they can be used to initialize multiline strings.
Not really sure why Enterprise library doesn't consider it as a valid SQL, you can use ;
to separate statements and then try like:
string query = @"USE Database;
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
SELECT * FROM table
WHERE table.column = 'sample';";
Or if you want to replace new line characters from your string then you can do:
query = query.Replace("\r\n", "");