Two data files have been deleted at the operating system level by accident. Your database is running in ARCHIVELOG mode and online backups are taken nightly. One of the data files that has been deleted belongs to the USERS tablespace on the other belongs to the SYSTEM tablespace. How can you recover from this situation？（） Shut down the database, restore the two data files and then start up the database. 。 Take the system and users tablespace offline, restore the two data files, recover the two datafiles, and then bring the SYSTEM and USERS tablespaces online. 。 Shut down the database, restore the two data files, start up the database in MOUNT mode, recover the two data files, and then alter the database open. 。 Take the SYSTEM and USERS tablespaces offline, recover the two datafiles and then bring the SYSTEM and USERS tablespaces online.。
井下每人每分钟供风量标准是（）。 2m3。 3m3。 4m3。 5m3。
曹禺一生共写下了剧本（）。 14部。 15部。 16部。 17部。
马氏体转变特点：
因工伤发生的（）费用，按照国家规定从工伤保险基金中支付。 治疗工伤期间的工资福利。 一次性伤残补助金。 一至四级伤残职工按月领取的伤残津贴。 劳动能力鉴定费。
着火必须有三要素，一是可燃料，二是火种，三是（）
