-I have got a headache.    

-No wonder. You ____ in front of the computer too long.    [ ]

A. work                                

B. are working    

C. have been working              

D. worked

( )是建设项目管理的基础。

A．项目环境和条件的调查分析

B．项目目标的分析和再论证

C．组织策划

D．合同策划