  As indicated by the observed X-ray flares, a great amount of energy could be
intermediately released from the postburst central engine of gamma-ray bursts
(GRBs). As a natural consequence, the GRB external shock could be energized
over and over. With such a multiple energy injection model, we explore the
unique X-ray afterglow light curve of GRB 050712, which exists four apparent
shallow decay plateaus. Together with three early X-ray flares, the central
engine of GRB 050712 is supposed to release energy at least seven times after
the burst. Furthermore we find that the energy released during four plateaus
are all on the same order of magnitude, but the luminosity decreases with time
significantly. These results may provide some interesting implications for the
GRB central engine.
