Present participle; Past participle - stumbling - stumbled Present - stumble - stumble - stumbles - stumble - stumble - stumble Past - stumbled - stumbled - stumbled - stumbled - stumbled - stumbled Future - will stumble - will stumble - will stumble - will stumble - will stumble - will stumble Present conditional - would stumble - would stumble - would stumble - would stumble - would stumble - would stumble Present Perfect - have stumbled - have stumbled - has stumbled - have stumbled - have stumbled - have stumbled Past Perfect - had stumbled - had stumbled - had stumbled - had stumbled - had stumbled - had stumbled Future Perfect - will have stumbled - will have stumbled - will have stumbled - will have stumbled - will have stumbled - will have stumbled Past conditional - would have stumbled - would have stumbled - would have stumbled - would have stumbled - would have stumbled - would have stumbled Imperative - - - stumble - - - - - - - -