7、IPV6 is (31)for ”Internet Protocol Version 6”.IPv6 is the “next generation”protocol designed by the IETF to (32) the current version Internet Protocol,IPVersion 4(“IPv4”).

　　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 beginning to have problems .Most importantly, there is a growing (33)of IPv4 addresses, which are needed by all new machines added to the internet.

　　IPv6 fixes a number of problems in IPv4,such as the (34)number of available. IPv4addreses.it also adds many improvements to IPv4 in areas such as routing and network autoconfiguration. IPv6 is expected to gradually replace IPv4,with the two coexisting for a number of years during a transition(35).

　　(31)A、 short B、abbreviate C、abbreviation D、initial

　　(32)A、substitution B、replace C、switchover D、swap

　　(33)A、scarcity B、lack C、deficiency D、shortage

　　(34)A、restrict B、limited C、confine D、imprison

　　(35)A、days B、period C、phase D、epoch

　　8、in the following essay,each blank has four choices.Choose the best answer and write down on the anser sheet .

　　Spread spectrum simply means that data is sent in small pieces over a number of the (36)frequencies available for use at any time in the specified rang.Devices using (37)spread spectrum(DSSS)communicate by (38)each byte of data into several parts and sending them concurrently on different (39).DSSS uses a lot of the available (75),about 22megaherts(MHZ).

　　(36)A、continuous B、high C、low D、discrete

　　(37)A、direct-sequence B、discrect-sequence

　　C、duplicate-sequence D、dedicate-sequence

　　(38)A、splitting B、combining C、packing D、compacting

　　(39)A、bits B、frequencies C、packets D、messages

　　(40)A、rate B、velocity C、bandwidth D、period

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