Present participle; Past participle - retarding - retarded Present - retard - retard - retards - retard - retard - retard Past - retarded - retarded - retarded - retarded - retarded - retarded Future - will retard - will retard - will retard - will retard - will retard - will retard Present conditional - would retard - would retard - would retard - would retard - would retard - would retard Present Perfect - have retarded - have retarded - has retarded - have retarded - have retarded - have retarded Past Perfect - had retarded - had retarded - had retarded - had retarded - had retarded - had retarded Future Perfect - will have retarded - will have retarded - will have retarded - will have retarded - will have retarded - will have retarded Past conditional - would have retarded - would have retarded - would have retarded - would have retarded - would have retarded - would have retarded Imperative - - - retard - - - - - - - -