For each blank, choose the best answer from the four choices and write down on the answer sheet. （66） is a protocol that a host uses to inform a router when it joins or leaves an Internet multicast group. （67） is an error detection code that most data communication networks use. （68） is an interior gateway protocol that uses a distance vector algorithm to propagate routing information. （69） 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. （70） is an identifier of a web page.

66（）

A．ICMP

B．SMTP

C．IGMP

D．ARP

下列代码的执行结果是( )。
class operator Test
public static void main(String[]args)
int x＝8；
short y=2；
system.out.println("xis"+ x + "，yis"+y)；

A．8和2

B．8.0和2.0

C．8和2.0

D．8.0和2