A. A*B=0 AND A<>B
B. (A=0 OR B=0 ) AND A<>B
C. A=0 AND B<>0 OR A<>0 AND B=0
D. A*B=0 AND (A=0 OR B=0 )
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A. A*B=0 AND A<>B
B. (A=0 OR B=0 ) AND A<>B
C. A=0 AND B<>0 OR A<>0 AND B=0
D. A*B=0 AND (A=0 OR B=0 )
(责任编辑:admin) |