早期的网络操作系统经历了由__________结构向主从结构的过渡。
参考答案：对等
The zoo is far away from my hotel. It me at least two hours to get there. [ ]
A. took
B. has take
C. takes
D. will take
校正线路的纵断面属于（）作业。
A.拨道
B.起道
C.改道
D.捣固
