  We perform a time-resolved spectral analysis of GRB 130606B within the
framework of a fast-cooling synchrotron radiation model with magnetic field
strength in the emission region decaying with time, as proposed by Uhm & Zhang.
The data from all time intervals can be successfully fit by the model. The same
data can be equally well fit by the empirical Band function with typical
parameter values. Our results, which involve only minimal physical assumptions,
offer one natural solution to the origin of the observed GRB spectra and imply
that, at least some, if not all, Band-like GRB spectra with typical Band
parameter values can indeed be explained by synchrotron radiation.
