论述往复活塞式压缩机机体振动较大的原因。
On Tuesday， a junior DBA dropped an important application user account， whose schema has important tables. You are asked to recover all the objects in the schema. On investigation， you find that the user account was dropped at 11：00 a.m. and Sunday’s backup is the most recent backup.Which flashback feature would you use？（） Flashback Drop。 Flashback Table。 Flashback Database。 Flashback Version Query。 Flashback Transaction Query。
相律具有什么限制性
闪点是评定可燃（）火灾危险程度的主要指标。 气体。 液体。 固体。
For Ethernet-to-Ethernet routers, such as the Cisco 831 behind a cable modem or DSL bridge, a traffic shaper is configured. This is required since the output 10-Mbps interface will not be congested. Which two statements are true?（） The parent policy-map shapes and the child policy-map queues.。 The mean-rate and burst-size must always be the same value.。 This will not work without a Dialer interface configured.。 The shaper provides congestion feedback.。
面向对象分析的核心在于（）
