Present participle; Past participle - understanding - understood Present - understand - understand - understands - understand - understand - understand Past - understood - understood - understood - understood - understood - understood Future - will understand - will understand - will understand - will understand - will understand - will understand Present conditional - would understand - would understand - would understand - would understand - would understand - would understand Present Perfect - have understood - have understood - has understood - have understood - have understood - have understood Past Perfect - had understood - had understood - had understood - had understood - had understood - had understood Future Perfect - will have understood - will have understood - will have understood - will have understood - will have understood - will have understood Past conditional - would have understood - would have understood - would have understood - would have understood - would have understood - would have understood Imperative - - - understand - - - - - - - -