For each blank, choose the best answer from the four choices and write down on the answer sheet.
(11) is a protocol that a host uses to inform a router when it joins Or leaves an Internet multicast group.
(12) is an error detection code that most data communication networks use.
(13) is an interior gateway protocol that uses a distance vector algorithm to propagate routing information.
(14) is a transfer mode in which all types of information are organized into fixed form cells on an asynchronous or non-periodic basis over a range of media.
(15) is an identifier of a web page.

A．ICMP

B．SMTP

C．IGMP

D．ARP

我国古代的荀子所著的艺术理论著作是______。

A．《尚书》
B．《书经》
C．《乐论》
D．《乐经》