高、低通滤波器通常以衰减（）dB的频率范围为通频带。
A. 小于3
B. 大于13
C. 大于23
D. 小于33
查看答案
某台离心式清水泵流量是300吨/时,叶轮外径为500毫米,现将叶轮直径50毫米, 流量是多少?
Which two statements are true about the Automatic Diagnostic Repository （ADR）？（）
A. The ADR base keeps all diagnostic information in binary format
B. SQL*Plus provides the ADRI script， which can be used to work with ADR
C. The ADR can be used for problem diagnosis only when the database is open
D. The ADR can be disabled by settting the DIAGNOSTIC_DEST parameter to null
E. The ADR can be used for problem diagnosis even when the database instance is down
F. The ADR base is shared across multiple instance
微信支付 
支付宝支付