IP协议是网际层的核心协议。
参考答案:对
For holidays,many people visit the Great Barrier Reef__________the northeast coast of Australia.[ ]
A. beyond
B. on
C. within
D. off
SW-220K型转向架构架采用()
A.U型焊接构架
B.H型焊接构架
C.U型铸钢构架
D.H型铸钢构架