I can thumbtack you can thumbtack she can thumbtack we can thumbtack you can thumbtack they can thumbtack
V-ing form
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
I can have thumbtacked you can have thumbtacked she can have thumbtacked we can have thumbtacked you can have thumbtacked they can have thumbtacked
V-ing perfect
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
I can't thumbtack you can't thumbtack she can't thumbtack we can't thumbtack you can't thumbtack they can't thumbtack
V-ing form
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
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
V-ing perfect
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
can I thumbtack? can you thumbtack? can she thumbtack? can we thumbtack? can you thumbtack? can they thumbtack?
V-ing form
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
can I have thumbtacked? can you have thumbtacked? can she have thumbtacked? can we have thumbtacked? can you have thumbtacked? can they have thumbtacked?
V-ing perfect
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
can't I thumbtack? can't you thumbtack? can't she thumbtack? can't we thumbtack? can't you thumbtack? can't they thumbtack?
V-ing form
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
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?
V-ing perfect
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?