  We have derived the closed system of averaged MHD-equations for general
oscillating flows, which are purely oscillating in the main approximation. We
have used the mathematical approach which combines the two-timing method and
the notion of the distinguished limit. Properties of the commutators are used
to simplify calculations. The direct connection with a vortex dynamo (or the
Langmuir circulations) has been demonstrated and a conjecture on the MHD-dynamo
has been formulated.
