下列说法:①﹣4的相反数;②﹣1与﹣4的乘积;③﹣4的绝对值;④﹣2的平方.其中结果与﹣(﹣4)相同的有[ ]
A.1个
B.2个
C.3个
D.4个
答案:D
.
Many wild animals in the world _____ , so we must take measures to protect them.
A.are dying out
B.have died out
C.died out
D.die out
TCP/IP参考模型分为4个层次,分别为( )。
A.应用层、传输层、网络层、物理层
B.应用层、会话层、网络层、主机—网络层
C.应用层、传输层、物理层、网络链路层
D.应用层、传输层、互连层、主机—网络层