Present participle; Past participle - slacking - slacked Present - slack - slack - slacks - slack - slack - slack Past - slacked - slacked - slacked - slacked - slacked - slacked Future - will slack - will slack - will slack - will slack - will slack - will slack Present conditional - would slack - would slack - would slack - would slack - would slack - would slack Present Perfect - have slacked - have slacked - has slacked - have slacked - have slacked - have slacked Past Perfect - had slacked - had slacked - had slacked - had slacked - had slacked - had slacked Future Perfect - will have slacked - will have slacked - will have slacked - will have slacked - will have slacked - will have slacked Past conditional - would have slacked - would have slacked - would have slacked - would have slacked - would have slacked - would have slacked Imperative - - - slack - - - - - - - -