某厂一台600MW机组，2008年3月15日12：37因计划降低出力10MW，持续2小时，其余时间全出力运行。该机组当月等效计划降低出力时间是（）小时。

A、0.03

B、0

C、2

D、1

Most of the older civilizations which flourished during the fifth century B.C. are died out.

A．they have died out

B．has died out

C．have died out

D．they had died out