下列关于因特网的网络互联层的说法，()是正确的。

(80)

(78)

(79)

(77)

(66)is　a　one-way　function　that　takes　an　arbitrarily　long　piece　of　plaintext　and　from　it　computes　a　fixed,length　bit　string.(67)is　a　protocol　that　most　USENET　machines　now　use　it　to　allow　news　articles　to　propagate　from　one　machine　to　another　over　a　reliable　connection.(68)is　an　approach　preferred　by　cable　TV　providers.　In　this　solution　the　fiber　terminates　at　an　opt~electrical　converter　and　the　final　segment　is　a　shared　coaxial　cable.(69)is　a　device　used　to　connect　two　separate　network　that　use　different　communication　protocol.(70)is　a　digital-to-digital　polar　encoding　method　in　which　the　signal　level　is　always　either　positive　or　negative.

(75)

(74)

Password　is　a　secret　series　of(69)that　enables　a　user　to　access　a　file,　computer,　or　program.　On　multi-user　systems,　each　user　must　enter　his　or　her　password　before　the　computer　will　respond　to(70).　The　password　helps　ensure　that(71)users　do　not　access　the　computer.　In　addition,　data　files　and　programs　may　require　a　password.

A　multimedia　system　allows　end　users　to　share,　transfer　and　process　a　variety　of　forms　of　in-　formation　in　a(75)manller.

SQL　Server　is　a　RDBMS(　Relational　Database　Management　System)made　by　Microsoft.　This　means　that　the　data　is　stored　in　two　dimensional(74)