有两台FMC，而FCC一次只使用一台FMC的数据。用于选择FMC的方法是：（）。
A. 由仪表源选择电门来选择FMC
B. 由FMC主电门来选择FMC
C. 总是选择左FMC
D. 根据自动驾驶通道衔接状况来选择FMC
Which two statements are true about the duplexing of the backups taken by RMAN？（）
A. It’s only supported for the backups performed on the tape
B. It is not supported for backup operations that produce image copies
C. Duplex backups need a parallelism for the device to be equal to number of copies
Duplex backups can be performed to either disk or tape， but cannot be performed on tape and disk simultaneously
特种设备作业人员要求做到“三不伤害”。即：不伤害他人，不伤害自己，不被他人伤害。
A. 正确
B. 错误
一般情况下，加工轴承衬多用青铜，因青铜承受载荷能力大，耐磨性能、导热性都比较好。
A. 正确
B. 错误
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