English verb conjugation
MUST THUMBTACK

Regular verb: thumbtack - thumbtacked - thumbtacked

Affirmation

Simple form	V-ing form
I must thumbtack you must thumbtack she must thumbtack we must thumbtack you must thumbtack they must thumbtack	I must be thumbtacking you must be thumbtacking she must be thumbtacking we must be thumbtacking you must be thumbtacking they must be thumbtacking
Perfect	V-ing perfect
I must have thumbtacked you must have thumbtacked she must have thumbtacked we must have thumbtacked you must have thumbtacked they must have thumbtacked	I must have been thumbtacking you must have been thumbtacking she must have been thumbtacking we must have been thumbtacking you must have been thumbtacking they must have been thumbtacking

Negation

Simple form	V-ing form
I mustn't thumbtack you mustn't thumbtack she mustn't thumbtack we mustn't thumbtack you mustn't thumbtack they mustn't thumbtack	I mustn't be thumbtacking you mustn't be thumbtacking she mustn't be thumbtacking we mustn't be thumbtacking you mustn't be thumbtacking they mustn't be thumbtacking
Perfect	V-ing perfect
I mustn't have thumbtacked you mustn't have thumbtacked she mustn't have thumbtacked we mustn't have thumbtacked you mustn't have thumbtacked they mustn't have thumbtacked	I mustn't have been thumbtacking you mustn't have been thumbtacking she mustn't have been thumbtacking we mustn't have been thumbtacking you mustn't have been thumbtacking they mustn't have been thumbtacking

Interrogative form

Simple form	V-ing form
must I thumbtack? must you thumbtack? must she thumbtack? must we thumbtack? must you thumbtack? must they thumbtack?	must I be thumbtacking? must you be thumbtacking? must she be thumbtacking? must we be thumbtacking? must you be thumbtacking? must they be thumbtacking?
Perfect	V-ing perfect
must I have thumbtacked? must you have thumbtacked? must she have thumbtacked? must we have thumbtacked? must you have thumbtacked? must they have thumbtacked?	must I have been thumbtacking? must you have been thumbtacking? must she have been thumbtacking? must we have been thumbtacking? must you have been thumbtacking? must they have been thumbtacking?

Interro-negative form

Simple form	V-ing form
mustn't I thumbtack? mustn't you thumbtack? mustn't she thumbtack? mustn't we thumbtack? mustn't you thumbtack? mustn't they thumbtack?	mustn't I be thumbtacking? mustn't you be thumbtacking? mustn't she be thumbtacking? mustn't we be thumbtacking? mustn't you be thumbtacking? mustn't they be thumbtacking?
Perfect	V-ing perfect
mustn't I have thumbtacked? mustn't you have thumbtacked? mustn't she have thumbtacked? mustn't we have thumbtacked? mustn't you have thumbtacked? mustn't they have thumbtacked?	mustn't I have been thumbtacking? mustn't you have been thumbtacking? mustn't she have been thumbtacking? mustn't we have been thumbtacking? mustn't you have been thumbtacking? mustn't they have been thumbtacking?