  In this paper, a modified Chaplygin gas model of unifying dark energy and
dark matter with exotic equation of state $p=B\rho-\frac{A}{\rho^{\alpha}}$
which can also explain the recent accelerated expansion of the universe is
investigated by the means of constraining the location of the peak of the CMBR
spectrum. We find that the result of CMBR measurements does not exclude the
nonzero value of parameter $B$, but allows it in the range $-0.35\lesssim
B\lesssim0.025$.
