The group of students went to the suburb, did some research work, and ________ the water

in the river    to see if it had been polluted.[      ]

A. proved          

B. boiled          

C. tested          

D. exchanged

下列选项中，不属于价值工程基本要素的是( )。

A．价值

B．功能

C．生产成本

D．寿命周期成本