Let R be a domain with quotiont eld K, and let N be a submodule of an R-module M. We say that N is powerful (strongly primary) if x; y 2 K and xyM N, then x 2 R or y 2 R (xM N or ynM N for some n 1). We show that a submodule with either of these properties is comparable to every prime submodule of M, also we show that an R-module M admits a powerful submodule if and only if it admits a strongly primary submodule. Finally we study nitely generated torsion free modules over domain each of whose prime submodules are strongly primary
