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 must not thumbtack you must not thumbtack she must not thumbtack we must not thumbtack you must not thumbtack they must not thumbtack	I must not be thumbtacking you must not be thumbtacking she must not be thumbtacking we must not be thumbtacking you must not be thumbtacking they must not be thumbtacking
Perfect	V-ing perfect
I must not have thumbtacked you must not have thumbtacked she must not have thumbtacked we must not have thumbtacked you must not have thumbtacked they must not have thumbtacked	I must not have been thumbtacking you must not have been thumbtacking she must not have been thumbtacking we must not have been thumbtacking you must not have been thumbtacking they must not 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
must I not thumbtack? must you not thumbtack? must she not thumbtack? must we not thumbtack? must you not thumbtack? must they not thumbtack?	must I not be thumbtacking? must you not be thumbtacking? must she not be thumbtacking? must we not be thumbtacking? must you not be thumbtacking? must they not be thumbtacking?
Perfect	V-ing perfect
must I not have thumbtacked? must you not have thumbtacked? must she not have thumbtacked? must we not have thumbtacked? must you not have thumbtacked? must they not have thumbtacked?	must I not have been thumbtacking? must you not have been thumbtacking? must she not have been thumbtacking? must we not have been thumbtacking? must you not have been thumbtacking? must they not have been thumbtacking?