单项选择题 （ ）is a document generated by the creating WBS process that support the WBS，which provides more detailed descriptions of the components in the WBS.

单项选择题 Validate Scope is the process of formalizing acceptance of completed（ ）.

单项选择题 （ ）is a computer technology that headsets,sometimes in combination with physical spaces or multi-projected environments,to generate realisitic images,sounds and other sensations that simulate a user’s physical presence in a virtual or imaginary environment.