Present participle; Past participle - lacking - lacked Present - lack - lack - lacks - lack - lack - lack Past - lacked - lacked - lacked - lacked - lacked - lacked Future - will lack - will lack - will lack - will lack - will lack - will lack Present conditional - would lack - would lack - would lack - would lack - would lack - would lack Present Perfect - have lacked - have lacked - has lacked - have lacked - have lacked - have lacked Past Perfect - had lacked - had lacked - had lacked - had lacked - had lacked - had lacked Future Perfect - will have lacked - will have lacked - will have lacked - will have lacked - will have lacked - will have lacked Past conditional - would have lacked - would have lacked - would have lacked - would have lacked - would have lacked - would have lacked Imperative - - - lack - - - - - - - -