在测量380V交流电动机绝缘时,选用()绝缘电阻表测量.
A. 500V
B. 1000V
C. 2500V
D. 5000V
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阻燃性是指在规定试验条件下,试样被燃烧,在撤去试验火源后,火焰的蔓延仅在限定范围内,且残焰或残灼在限定时间内能自行熄灭的特性。
A. 正确
B. 错误
无绝缘自动闭塞区段,禁止机车全部停留在调谐区内,特殊情况确须停留时,作业程序为:在()短路铜线→汇报车站或调度报告停车位置→撤除短接铜线→报告车站或调度开车。
A. 前方调谐区外
B. 后方调谐区外
C. 调谐区内
You issued the following command: ALTER TABLE SCOTT.EMP SHRINK SPACE; The SCOTT.EMP table is stored in the DATA1 tablespace that has the following properties: DATA1 is a read/write tablespace. DATA1 is not autoextensible to an unlimited size. DATA1 is online. Segment space management for the DATA1 tablespace is manual. You issued the ALTER TABLE SCOTT.EMP SHRINK SPACE; command that generates the following error: ORA-10635: Invalid segment or tablespace type What could be the reason for the failure of the command?()
A. The tablespace, DATA1, is not read-only.
B. The tablespace, DATA1, is not autoextensible.
C. The tablespace, DATA1, is not offline.
D. The segment space management for the tablespace, DATA1, is manual.