世界三大人种划分的主要依据[ ]

A、经济文化程度

B、风俗习惯

C、语言

D、人类体质特征

Rebaselining may be required in cost control when （）.

A．CVs are severe, and a realistic measure of performance is needed

B．revised cost estimates are prepared and distributed to stakeholders

C．corrective action must be taken to bring expected future performance in line with the project plan

D．EAC shows that additional funds are needed to complete the project even if a scope change is not needed