oracle11g 空表不能exp导出的问题

--查询所有的空表
select table_name from user_tables where NUM_ROWS=0; 
--生成执行语句
select 'alter table '||table_name||' allocate extent;' from user_tables where num_rows=0 ;
--复制上面生成的语句，如下所示
alter table E2USER_STATE allocate extent; 
alter table ENTERPRISE_E2USER allocate extent; 
alter table ENTERPRISE_INFO_TYPE allocate extent; 
alter table ENTERPRISE_MAPMARK allocate extent; 
alter table ENTERPRISE_NEEDTASK allocate extent; 
alter table ENTERPRISE_PICTURE allocate extent; 
alter table ENTERPRISE_REPORT allocate extent; 
alter table ENTERPRISE_REPORT_TYPE allocate extent; 
alter table ENTERPRISE_TEAM allocate extent; 
alter table FROMUSER_ADJUNCT_TARGET allocate extent; 
alter table FROMUSER_OFFER allocate extent; 
alter table NEEDTASK_TYPE allocate extent; 
alter table SYS_PRIVILEGE allocate extent; 
alter table SYS_RELEVANCE_RESOURCE allocate extent; 
alter table SYS_RELEVANCE_TARGET allocate extent; 
alter table SYS_RESOURCE_TYPE allocate extent; 
alter table TASK_FEEDBACK allocate extent; 
alter table TASK_MYTASKTYPE allocate extent;