如图，直角坐标系中，△ABC的顶点都在网格点上，

（1）写出点A、B的坐标：A（______，______）、B（______，______）

（2）△ABC的面积为______平方单位．

（3）将△ABC先向右平移1个单位长度，再向下平移1个单位长度，得到△A′B′C′，在图中作出平移后的图形．

（4）则A′B′C′的三个顶点坐标分别是A′（______、______）、B′（______、______）、C′（______、______）

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．connections 

B．protocols 

C．networks 

D．address