Present participle; Past participle - pre-existing - pre-existed Present - pre-exist - pre-exist - pre-exists - pre-exist - pre-exist - pre-exist Past - pre-existed - pre-existed - pre-existed - pre-existed - pre-existed - pre-existed Future - will pre-exist - will pre-exist - will pre-exist - will pre-exist - will pre-exist - will pre-exist Present conditional - would pre-exist - would pre-exist - would pre-exist - would pre-exist - would pre-exist - would pre-exist Present Perfect - have pre-existed - have pre-existed - has pre-existed - have pre-existed - have pre-existed - have pre-existed Past Perfect - had pre-existed - had pre-existed - had pre-existed - had pre-existed - had pre-existed - had pre-existed Future Perfect - will have pre-existed - will have pre-existed - will have pre-existed - will have pre-existed - will have pre-existed - will have pre-existed Past conditional - would have pre-existed - would have pre-existed - would have pre-existed - would have pre-existed - would have pre-existed - would have pre-existed Imperative - - - pre-exist - - - - - - - -