  The features of the emissions of light particles (LP), charged particles
(CP), intermediate mass fragments (IMF) and the largest fragment (MAX) are
investigated for $^{129}Xe$ as functions of temperature and 'freeze-out'
density in the frameworks of the isospin-dependent lattice gas model and the
classical molecular dynamics model. Definite turning points for the slopes of
average multiplicity of LP, CP and IMF, and of the mean mass of the largest
fragment ($A_{max}$) are shown around a liquid-gas phase transition temperature
and while the largest variances of the distributions of LP, CP, IMF and MAX
appear there. It indicates that the cluster emission rate can be taken as a
probe of nuclear liquid--gas phase transition. Furthermore, the largest
fluctuation is simultaneously accompanied at the point of the phase transition
as can be noted by investigating both the variances of their cluster
multiplicity or mass distributions and the Campi scatter plots within the
lattice gas model and the molecular dynamics model, which is consistent with
the result of the traditional thermodynamical theory when a phase transition
occurs.
