  The employment of interpolating currents of existed studies of four-quark
state and glueball with QCD sum rule approach is analyzed. In terms of suitable
currents, the masses of the lowest lying scalar and pseudo-scalar glueball were
determined. The masses of some tetraquark states and their first orbital
excitations were obtained through a combination of the sum rule with the
constituent quark model. Exotica possibility of the new observations by BES is
discussed.
