● Typically, an IP address refers to an individual host on a particular network. IP also accommodates addresses that refer to a group of hosts on one or more networks. Such addresses are referred to as multicast addresses, and the act of sending a packet from a source to the members of a （71）group is referred to as multicasting. Multicasting done （72）the scope of a single LAN segment is straightforward. IEEE 802 and other LAN protocols include provision for MAC-level multicast addresses. A packet with a multicast address is transmitted on a LAN Segment. Those stations that are members of the （73）multicast group recognize the multicast address and （74）the packet. In this case, only a single copy of the packet is ever transmitted. This technique works because of the （75）nature of a LAN: A transmission from any one station is received by all other station on the LAN.
（69）A.numerous
B.only
C.single
D.multicast
（70）A.within
B.out of
C.beyond
D.cover
（71）A.different
B.unique
C.special
D.corresponding
（72）A.reject
B.accept
C.discard
D.transmit
（73）A.multicast
B.unicast
C.broadcast
D.multiple unicast

● MVC（Model——View——Controller，模型——视图——控制器）是一种广泛流行的软件设计模式，也是J2EE平台上推荐的一种设计模型。其中，（）主要表现用户界面，（）用来描述核心业务逻辑。
（74）A.模型
B.视图
C.控制器
D.视图和控制器
（75）A.模型
B.视图
C.控制器
D.视图和控制器