Present participle; Past participle - heightening - heightened Present - heighten - heighten - heightens - heighten - heighten - heighten Past - heightened - heightened - heightened - heightened - heightened - heightened Future - will heighten - will heighten - will heighten - will heighten - will heighten - will heighten Present conditional - would heighten - would heighten - would heighten - would heighten - would heighten - would heighten Present Perfect - have heightened - have heightened - has heightened - have heightened - have heightened - have heightened Past Perfect - had heightened - had heightened - had heightened - had heightened - had heightened - had heightened Future Perfect - will have heightened - will have heightened - will have heightened - will have heightened - will have heightened - will have heightened Past conditional - would have heightened - would have heightened - would have heightened - would have heightened - would have heightened - would have heightened Imperative - - - heighten - - - - - - - -