目前我国60kg/m标准钢轨的长度有（）两种。
A.4.5m和6m
B.6m和12.5m
C.12.5m和25m
D.6m和25m
参考答案：C
现代旅游业诞生的标志是1865年托马斯·库克创办的世界第一家旅行社。
I ________ it myself ________ your homework.
A．prefer do; rather than copy
B．prefer doing; than copy
C．would do; rather than copy
D．would rather do; than copy
