根据下面的文字资料回答 68～72 题

For each blank．choose the best answerfrom the four choices and write down on the answer sheet． 

（　1　）is a protocol that a host uses toinform. a router when it joins or leaves an Internet muhicast group．

（　2　） is an error detection code that most data communication networks use．

（　3　）is an interior gateway protocol that uses a distance vector algorithm topropagate routing information．

（　4　）is a transfer mode in which all types of information ate organized intofixed form. cells onan asynchronous or non－periodic basis over a range of media．

（　5　）is an identifier of a web page．

第68题：文中（　1　）处正确的答案是（　　）。

第70题：文中（　3　）处正确的答案是（　　）。

第71题：文中（　4　）处正确的答案是（　　）。

第72题：文中（　5　）处正确的答案是（　　）。

根据下面的文字资料回答 68～72 题

For each blank．choose the best answerfrom the four choices and write down on the answer sheet． 

（　1　）is a protocol that a host uses toinform. a router when it joins or leaves an Internet muhicast group．

（　2　） is an error detection code that most data communication networks use．

（　3　）is an interior gateway protocol that uses a distance vector algorithm topropagate routing information．

（　4　）is a transfer mode in which all types of information ate organized intofixed form. cells onan asynchronous or non－periodic basis over a range of media．

（　5　）is an identifier of a web page．

第68题：文中（　1　）处正确的答案是（　　）。

第69题：文中（　2　）处正确的答案是（　　）。

第66题：文中（　4　）处正确的答案是（　　）。

第67题：文中（　5　）处正确的答案是（　　）。

第65题：文中（　3　）处正确的答案是（　　）。

：根据下面的文字资料回答 63～67 题

In low-speed network，it is usually adequate to wait for congestion to occur and

then react to it by telling the source of packets to slow down．In high-speed

networks，this approach oftenworks poorly，because in the（　1　）between sending the

notification and notification arriving at the source，thousands of

第64题：文中（　2　）处正确的答案是（　　）。