数据库系统由数据库、(5)和硬件等组成，数据库系统是在(6)的基础上发展起来的。数据库系统由于能减少数据冗余，提高数据独立性，并集中检查(7)，由此获得广泛的应用。数据库提供给用户的接口是(8)，它具有数据定义、数据操作和数据检查功能，可独立使用，也可嵌入宿主语言使用。(9)语言已被国际标准化组织采纳为标准的关系数据库语言。

(75)

(76)

(77)

In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

 To a router, a flow is a(71)of packets that share the same characterstics, such as traveling the same(72), using the same(73), having the same kind of security, and so on. A router that supports the handling of flow labels has a(74)table. The table has an entry for each Active flow label; each entry defines the(75)required by the corresponding flow label.

(74)

(70)

(71)

(72)

(69)

In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

 In low - speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high - speed networks, this approach often works poorly, because in the(66)between sending the notification and notification arriving at the source, thousands of additional(67)may arrive. In ATM network, a major tool for preventing(68)is(69)control. When a host wants a new virtual(70), it must describe the traffic to be offered and the service expected.