单项选择题
A.OPEN(UNIT=3,FILE=AA.DAT,STATUS=NEW) B.OPEN(UNIT=3,FILE=AA.DAT,STATUS=OLD. C.OPEN(3,FILE=′AA.DAT′,STATUS=′NEW′) D.OPEN(D,FILE=′AA.DAT′,STATUS=′OLD′)
A.OSI B.IPX/SPX C.ICP/IP D.CSMA/CD