My book, Vector Mechanics for Engineers: Statics and Dynamics 12th Edition, states in the plain motion of a rigid body, the motion of the rigid body is completely defined by the resultant force and resultant moment about G acting on the body. But it also states
We also note, as we did earlier, that the system of the external forces does not, in general, reduce to a single vector m¯ a attached at G. Therefore, in the general case of the plane motion of a rigid body, the resultant of the external forces acting on the body does not pass through the mass center of the body.
Is it because the resultant moment is not zero at G in general, and if the resultant force doesn't pass through G, we can replace it with the same vector attached at G and the couple ? Is that right?