USER1 grants SELECT and UPDATE privileges on USER1.EMP to USER2。
SYS executes this command：
SQL> REVOKE SELECT ON user1.emp FROM user1;
What will be the outcome?
A)It will succeed and USER2 will be unable to perform SELECT on USER1.EMP
B)It will succeed and USER2 will be unable to perform sELECT or UPDATE on USER1.EMP because updates require select be done internally
C)It will fail because sys can not revoke object privileges for other users
D)It will fail because USER1 owns USER1.EMP
Answer: D
赵：属主对自己拥有的对象的权限不可被收回
