ATM(异步传输模式)技术中“异步”的含义是(48)。

(38)

(37)

(36)

(35)

In the following essay, each blank has four choices. Choose the most suitable one from the four choices and write down in the answer sheet.

 Open Shortest Path First(OSPF)is a(71)routing algorithm that(72)work done on the OSI IS-IS intradomain routing protocol. This routing, as compared to distance-vector routing, requires(73)processing power. The(74)algorithm is used to calculate routes. OSPF routing table updates only take place when necessary,(75)at regular intervals.

(32)

(33)

(31)

(30)

Packet-switching wireless networks are preferable(66)when transmissions are(67)bemuse of the way charges are(68)per packet. Circuit-switched networks are preferable for transferring large files or for other lengthy transmissions because customers are(69)for the(70)of time they use the network.