在计算财务净现值时，采用的折现率为（）。

A.社会折现率

B.经济折现率

C.影子汇率

D.行业基准收益率

Computer systems consist of two very different types of elements：Hardware，which includes all the physical things that can be touched and（），which tells thehardware how to do.

A.Software

B.Courseware

C.Operatingsystem

D.I/Odevices