ACL Question: normal user howto restrict root's permition ?

[Gang Xu <gang.xu@xxxxxxxxxxxx>]

Hi, all~

I have a question:
normal users how to restrict root permition of a file(own by normal user)?

[background]:
  Kernel 2.6.7 (compile with ACL)
  mount / with acl option
  skywind is a normal user in system

[object]:
  normal user skywind restrict root's read permition by using ACL.

[detailed]:
  skywind@localhost:~$ cat 123 > /tmp/test
  skywind@localhost:~$ chmod 700 /tmp/test
  skywind@localhost:~$ setfacl u:root:--- /tmp/test
  skywind@localhost:~$ su -
  localhost:~# cat /tmp/test
  123
  localhost:~#

[result is:] 
  root can read the /tmp/test

Why?
I don't want root read the /tmp/test
How to do?

Could anyone  help me?
Very very thankx~~~~~
:-)

--
Skywind