  In this work, we study the masses of $Qq\bar Q\bar q'$ states with
J^{PC}=0^{++}, 1^{++}, 1^{+-} and 2^{++} in the chiral SU(3) quark model, where
Q is the heavy quark (c or b) and q (q') is the light quark (u, d or s).
According to our numerical results, it is improbable to make the interpretation
of $[cn\bar c\bar n]_{1^{++}}$ and $[cn\bar c\bar n]_{2^{++}}$ (n=u, d) states
as X(3872) and Y(3940), respectively. However, it is interesting to find the
tetraquarks in the $bq\bar b\bar q'$ system.
