Present participle; Past participle - jackknifing - jackknifed Present - jackknife - jackknife - jackknifes - jackknife - jackknife - jackknife Past - jackknifed - jackknifed - jackknifed - jackknifed - jackknifed - jackknifed Future - will jackknife - will jackknife - will jackknife - will jackknife - will jackknife - will jackknife Present conditional - would jackknife - would jackknife - would jackknife - would jackknife - would jackknife - would jackknife Present Perfect - have jackknifed - have jackknifed - has jackknifed - have jackknifed - have jackknifed - have jackknifed Past Perfect - had jackknifed - had jackknifed - had jackknifed - had jackknifed - had jackknifed - had jackknifed Future Perfect - will have jackknifed - will have jackknifed - will have jackknifed - will have jackknifed - will have jackknifed - will have jackknifed Past conditional - would have jackknifed - would have jackknifed - would have jackknifed - would have jackknifed - would have jackknifed - would have jackknifed Imperative - - - jackknife - - - - - - - -