How can I see the values of bind variables in SQL statements that we find through Top Activity button in Enterprise Manager Database Control?

E.g:
SELECT DISTINCT MAX(MRT.MRNCODE) FROM MRNITEMS MRT,MATERIALRECEIPTNOTE MNS WHERE MRT.MRNCODE = MNS.MRNCODE AND MRNDATE = :b1 AND PURCHASEFWDDATE IS NOT NULL