“…As the development of control theory, controllability problems for stochastic systems drew more and more attention in recent years(see [2,5,7,8,9,10,11,12,13,14,17,20,21,22,23] and the rich references therein). Especially, the controllability problem for linear stochastic differential equations are studied in [2,4,8,14,17,21]. In [17], it is proved that (2) is exact controllable only if the rank of D is n. Moreover, a sufficient condition (in the form of rank condition) for exact controllability of (2) is given in [17].…”