Present participle; Past participle - collapsing - collapsed Present - collapse - collapse - collapses - collapse - collapse - collapse Past - collapsed - collapsed - collapsed - collapsed - collapsed - collapsed Future - will collapse - will collapse - will collapse - will collapse - will collapse - will collapse Present conditional - would collapse - would collapse - would collapse - would collapse - would collapse - would collapse Present Perfect - have collapsed - have collapsed - has collapsed - have collapsed - have collapsed - have collapsed Past Perfect - had collapsed - had collapsed - had collapsed - had collapsed - had collapsed - had collapsed Future Perfect - will have collapsed - will have collapsed - will have collapsed - will have collapsed - will have collapsed - will have collapsed Past conditional - would have collapsed - would have collapsed - would have collapsed - would have collapsed - would have collapsed - would have collapsed Imperative - - - collapse - - - - - - - -