文中（4 ）處正確的答案是（）。

A．full-duplex

B．half-duplex

C．simplex

D．complex

A．FTP

B．UDP

C．IP

D．HTTP

by the IETF to(72)the current version Inernet Protocol, IP Version 4. Most of today's internet uses Ipv4, which is now nearly twenty years old. Ipv4 has been remarkably resilient in spite of its age, but it is beginging to have problems. Most importantly, there is a growing(73)of Ipv4 addresses, which are needed by all new machines added to the Internet. Ipv6 fixs a number of problems in Ipv4, shch as the(74)number of available Ipv4 addresses. It also adds many improvements to Ipv4 in areas such as souting and network autoconfiguration. Ipv6 is expected to gradually replace Ipv4, with the two coexing for a number of years during a transition(75)A.

A．short

B．a(chǎn)bbreviate

C．a(chǎn)bbreviation

D．initial

A．substitution

B．replace

C．switchover

D．swap

A．scarcity

B．lack

C．deficiency

D．shortage

A．restrict

B．limited

C．imprison

D．confine

A．period

B．days

C．epoch

D．phase

鏈表不具備的特點是______。

A．可隨機訪問任何一個元素

B．插入、刪除操作不需要移動元素

C．無須事先估計存儲空間的大小

D．所需存儲空間與線性表長度成正比

矩陣壓縮存儲的主要目的是______。

A．方便運算

B．節(jié)省存儲空間

C．降低計算復(fù)雜度

D．提高運算效率

判斷“鏈?zhǔn)疥犃袨榭铡钡臈l件是______(front為頭指針，rear為尾指針)。

A．front==NULL

B．rear==NULL

C．front==rear

D．front!=rear