"The river flows sluggishly under the bridge."
Translation:Sub ponte flumen languide fluit.
sub + ( Accusative, Ablative ) • Which Case depends on whether or not the expression context means the [ Subject - Verb - Preposition: Direct / Indirect Object ] interaction is Transitive in nature. Does the Preposition transfer the Subject's Verb action to impact or bear upon the Object? If yes, then Transitive - Direct Object in the Accusative Case. If no, then Intransitive - Indirect Object in Ablative Case.