(31) analysis emphasizes the drawing of pictorial system models to document and validate both existing and/or proposed systems. Ultimately, the system models become the (32) for designing and constructing an improved system. (33) is such a technique. The emphasis in this technique is process-centered. Systems analysts draw a series of process models called (34) . (35) is another such technique that integrates data and process concerns into constructs called objects.
（34）是（）
A.PERT
B.DFD
C.ERD
D.UML
