设某流水线计算机主存的读/写时间为100ns，有一个指令和数据合一的Cache，已知该Cache的读/写时间为10ns，取指令的命中率为98%，取数的命中率为95%。在执行某类程序时，约有1/5指令需要存 /取一个操作数。假设指令流水线在任何时候都不阻塞，则设置Cache后，每条指令的平均访存时间约为(23)。

(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.