学校组织三年级的6名老师和534名学生乘车外出参观博物馆，共租用9辆客车，如果每辆客车的人数同样多，那么：

（1）每辆客车乘坐多少人？

（2）公园门票每人6元，买门票要用多少元？

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 1960s it has also been implemented on a wide variety of no-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 these changes. 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 to the basic IPv6 features requited by TCP and UDP applications, including multicasting, while introducing a minimums of change into the system and providing complete （75） for existing IPv4 applications.

A．applications 

B．networks 

C．protocols 

D．systems