thanks JayJayECL and jpfi, Yes, I knew it should work if I chose not to inherit rule from parent option, however, what I really want is to only make "Version Testing" folder removing versionable aspect but not for folders under "Version Testing" folders. Because we assumed only few folders would take out versionable aspect.
And now I am trying to use a work around that create new aspect with a field "folderVersionable" (boolean value) for every folder, and implement an actionExecutor in java (rule action in java) to add versionable aspect whenever the folder properties "folderVersionable" value is true. Whenever the user wanna bypass the "add versionable aspect" action, they only have to update the properties "folderVersionable" value to false.
Final thing is, I am also thinking how to prevent that rule (or system default rules, not user rules) from being deleted by the folder coordinator ???!!!!!!