  We analytically study the optomechanically induced transparency (OMIT) in the
$N$-cavity system with the \textit{N}th cavity driven by pump, probing laser
fields and the \textit{1}st cavity coupled to mechanical oscillator. We also
consider that one atom could be trapped in the \textit{i}th cavity. Instead of
only illustrating the OMIT in such a system, we are interested in how the
number of OMIT windows is influenced by the cavities and the atom and what
roles the atom could play in different cavities. In the resolved sideband
regime, we find that, the number of cavities precisely determines the maximal
number of OMIT windows. It is interesting that, when the two-level atom is
trapped in the even-labeled cavity, the central absorptive peak (odd $N$) or
dip (even $N$) is split and forms an extra OMIT window, but if the atom is
trapped in the odd-labeled cavity, the central absorptive peak (odd $N$) or dip
(even $N$) is only broadened and thus changes the width of the OMIT windows
rather than induces an extra window.
