下列不属于数据电文的是（）。 ["电子邮件","手机短信","电报","书面合同"]
Your database is running under automatic undo management and the UNDO_RETENTION parameter is set to 900 sec. You executed the following command to enable retention guarantee： SQL> ALTER TABLESPACE undotbs1 RETENTION GUARANTEE; What effect would this statement have on the database？（） ["The extents in undo tablespace retain data until the next full database backup.","The extents containing committed data in the undo tablespace are never overwritten.","The extents which no longer contain uncommitted data in the undo tablespace are not overwritten for at least15 minutes.","The extents containing committed data in the undo tablespace are not overwritten until the instance is shut down."]
货车厂、段修时，比例阀质量保证期限为（）。 ["6个月","1年","1个辅修期","1个段修期"]
通风及空调工程材料进入施工现场后，必须由供货商、（）、施工单位的代表共同对其进行实物到货验收。 ["建设单位","监检单位","安全部门","监理"]
Given: What is the result?（） ["B","The code runs with no output.","Compilation fails because of an error in line 12.","Compilation fails because of an error in line 15.","Compilation fails because of an error in line 18."]
放牧家畜的营养管理有何意义。
