English verb conjugation
CAN THUMBTACK

Regular verb: thumbtack - thumbtacked - thumbtacked

Affirmation

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

Negation

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

Interrogative form

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

Interro-negative form

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