Present participle; Past participle - thumbtacking - thumbtacked Present - thumbtack - thumbtack - thumbtacks - thumbtack - thumbtack - thumbtack Past - thumbtacked - thumbtacked - thumbtacked - thumbtacked - thumbtacked - thumbtacked Future - will thumbtack - will thumbtack - will thumbtack - will thumbtack - will thumbtack - will thumbtack Present conditional - would thumbtack - would thumbtack - would thumbtack - would thumbtack - would thumbtack - would thumbtack Present Perfect - have thumbtacked - have thumbtacked - has thumbtacked - have thumbtacked - have thumbtacked - have thumbtacked Past Perfect - had thumbtacked - had thumbtacked - had thumbtacked - had thumbtacked - had thumbtacked - had thumbtacked Future Perfect - will have thumbtacked - will have thumbtacked - will have thumbtacked - will have thumbtacked - will have thumbtacked - will have thumbtacked Past conditional - would have thumbtacked - would have thumbtacked - would have thumbtacked - would have thumbtacked - would have thumbtacked - would have thumbtacked Imperative - - - thumbtack - - - - - - - -