题目内容

根据负荷的容量和分布，配变电所宜靠近负荷中心。当配电电压为35kV时也可采用（）。

A. 旋降至220V配电电压
B. 旋降至380V配电电压
C. 旋降至220/380V配电电压
D. 直降至220/380V配电电压

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中鹅特点是消化道容积已增大，消化能力强，采食量大，对外界环境的适应性增强。也是大羽和骨肉迅速生长的阶段（）

A. 正确
B. 错误

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Your database is in ARCHIVELOG mode. On Friday evening， you perform an online database backup by using the BACKUP DATABASE command at the Recovery Manager （RMAN） prompt and close the database. On Monday， the System Administrator informs you about the failure of two hard disks. One of the lost disks contains two datafiles， HR1.DBF and HR2.DBF， both of which belong to a read/write tablespace named HR. The disk also contains a datafile， USERS.DBF， which belongs to a read/write tablespace named USERS. You need to restore and recover the database backup that was performed on Friday evening. After mounting the database， you issue the following RMAN commands： RMAN>RESTORE DATABASE； RMAN>RECOVER DATABASE； After successfully executing these RMAN commands， you issue the following statement using SQL*Plus： SQL>ALTER DATABASE OPEN； You receive the following errors when attempting to open the database： ORA-01157： cannot identify/lock data file 10 see DBWR trace file ORA-01110： data file 10： ’D：\USERS.DBF’ What is the cause of these errors？（）

A. The USERDBF datafile is corrupted and cannot be restored by RMA
B. The USERDBF datafile was not backed up using the RMAN BACKUP DATABASE command.
C. The USERDBF datafile was not restored using the RMAN RESTORE DATABASE command.
D. The USERDBF datafile was not recovered using the RMAN RECOVER DATABASE command.

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更换机轮时需要（）

A. 用轮轴千斤顶顶起对应的起落架
B. 用飞机千斤顶三点顶起飞机
C. 以上都可以

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拔出备用放手柄，通过钢索（）

A. 松开主起落架舱门上锁
B. 打开收放系统的循环活门
C. 以上所有

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根据负荷的容量和分布，配变电所宜靠近负荷中心。当配电电压为35kV时也可采用（）。

A. 旋降至220V配电电压 B. 旋降至380V配电电压 C. 旋降至220/380V配电电压 D. 直降至220/380V配电电压

中鹅特点是消化道容积已增大，消化能力强，采食量大，对外界环境的适应性增强。也是大羽和骨肉迅速生长的阶段（）

更换机轮时需要（）

拔出备用放手柄，通过钢索（）

A. 旋降至220V配电电压
B. 旋降至380V配电电压
C. 旋降至220/380V配电电压
D. 直降至220/380V配电电压