Present participle; Past participle - knuckling - knuckled Present - knuckle - knuckle - knuckles - knuckle - knuckle - knuckle Past - knuckled - knuckled - knuckled - knuckled - knuckled - knuckled Future - will knuckle - will knuckle - will knuckle - will knuckle - will knuckle - will knuckle Present conditional - would knuckle - would knuckle - would knuckle - would knuckle - would knuckle - would knuckle Present Perfect - have knuckled - have knuckled - has knuckled - have knuckled - have knuckled - have knuckled Past Perfect - had knuckled - had knuckled - had knuckled - had knuckled - had knuckled - had knuckled Future Perfect - will have knuckled - will have knuckled - will have knuckled - will have knuckled - will have knuckled - will have knuckled Past conditional - would have knuckled - would have knuckled - would have knuckled - would have knuckled - would have knuckled - would have knuckled Imperative - - - knuckle - - - - - - - -