This research report tackles several aspects of the association of French motion verbs and spatial PPs. We first recall the main notions used in order to characterize strict motion predicates -change of basic locative relation and change of placement- and show how these notions combine in the verbs' semantic content. The possibility, for the different verbs, of appearing in implicit landmark constructions is studied and we show that these constructions depend on the spatio-temporal structure of the verbs and on various other factors. With regard to the association of verbs and PPs with opposite polarities, this turns out to be in close correlation with the existence of an implicit use of the verb. An analysis of French prepositions appearing in dynamic descriptions is then proposed, in the light of the notions of change of relation and change of placement. Finally, a non-exhaustive list of asymmetries/dissymmetries between initial and final changes of relation and placement is provided and, here again, the spatio-temporal structure of motion events proves to be a fundamental factor, possibly at the source of several other aspects of asymmetry.