The de facto standard application program interface (API) for TCP/IP applications is the "sockets" interface. Although this API was developed for ___71___ in the early 1980s. it has also been implemented on a wide variety of non-Unix systems. TCP/IP ___72___ written using the sockets API have in the past enjoyed a high degree of portability and we would like the same ___73___ with IPv6 applications. But changes are required to the sockets API to support IPv6 and this memo describes thesechanges. These include a new socket address structure to carry IPv6 ___74___. new address conversion functions, and some new socket options. These extensions are designed to provide Access tothe basic IPv6 features required by TCP and UDP applications, including multicasting, while introducing a minimum of change into the system and providing complete ___75___ for existing IPv4 applications.

72（）

A．applications

B．networks

C．protocols

D．systems

男性，60岁，肥胖。睡眠时频繁翻身，肢体运动，时而惊醒，突然又落枕而睡，鼾声响亮，有时家人发现口鼻气流停止。自觉困倦无力，晨起头痛，记忆力、判断力下降。

目前常用的有效疗法是（）

A.经鼻持续正压气道通气

B.经口持续正压气道通气

C.经鼻持续负压气道通气

D.经鼻间断正压气道通气

E.经口间断正压气道通气