  As a continuation to our previous work [9, 10], we consider the domino tiling
problem with impurities. (1) if we have more than two impurities on the
boundary, we can compute the number of corresponding perfect matchings by using
the hitting matrix method[4]. (2) we have an alternative proof of the main
result in [9] and result in (1) above using the formula by Kenyon-Wilson [6, 7]
of counting the number of groves on the circular planar graph. (3) we study the
behavior of the probability of finding the impurity at a given site when the
size of the graph tends to infinity, as well as the scaling limit of those.
