You'd better go there by train. The train ticket is ________ the airplane ticket.[      ]

A. as cheap three times as      

B. as three times cheap as

C. three times cheaper than      

D. cheaper three times than

正式认可项目的范围属于项目范围管理过程中的( )。

A．启动

B．范围定义

C．范围核实

D．范围变更控制