I may thumbtack you may thumbtack he may thumbtack we may thumbtack you may thumbtack they may thumbtack
V-ing form
I may be thumbtacking you may be thumbtacking he may be thumbtacking we may be thumbtacking you may be thumbtacking they may be thumbtacking
Perfect
I may have thumbtacked you may have thumbtacked he may have thumbtacked we may have thumbtacked you may have thumbtacked they may have thumbtacked
V-ing perfect
I may have been thumbtacking you may have been thumbtacking he may have been thumbtacking we may have been thumbtacking you may have been thumbtacking they may have been thumbtacking
Negation
Simple form
I mayn't thumbtack you mayn't thumbtack he mayn't thumbtack we mayn't thumbtack you mayn't thumbtack they mayn't thumbtack
V-ing form
I mayn't be thumbtacking you mayn't be thumbtacking he mayn't be thumbtacking we mayn't be thumbtacking you mayn't be thumbtacking they mayn't be thumbtacking
Perfect
I mayn't have thumbtacked you mayn't have thumbtacked he mayn't have thumbtacked we mayn't have thumbtacked you mayn't have thumbtacked they mayn't have thumbtacked
V-ing perfect
I mayn't have been thumbtacking you mayn't have been thumbtacking he mayn't have been thumbtacking we mayn't have been thumbtacking you mayn't have been thumbtacking they mayn't have been thumbtacking
Interrogative form
Simple form
may I thumbtack? may you thumbtack? may he thumbtack? may we thumbtack? may you thumbtack? may they thumbtack?
V-ing form
may I be thumbtacking? may you be thumbtacking? may he be thumbtacking? may we be thumbtacking? may you be thumbtacking? may they be thumbtacking?
Perfect
may I have thumbtacked? may you have thumbtacked? may he have thumbtacked? may we have thumbtacked? may you have thumbtacked? may they have thumbtacked?
V-ing perfect
may I have been thumbtacking? may you have been thumbtacking? may he have been thumbtacking? may we have been thumbtacking? may you have been thumbtacking? may they have been thumbtacking?
Interro-negative form
Simple form
mayn't I thumbtack? mayn't you thumbtack? mayn't he thumbtack? mayn't we thumbtack? mayn't you thumbtack? mayn't they thumbtack?
V-ing form
mayn't I be thumbtacking? mayn't you be thumbtacking? mayn't he be thumbtacking? mayn't we be thumbtacking? mayn't you be thumbtacking? mayn't they be thumbtacking?
Perfect
mayn't I have thumbtacked? mayn't you have thumbtacked? mayn't he have thumbtacked? mayn't we have thumbtacked? mayn't you have thumbtacked? mayn't they have thumbtacked?
V-ing perfect
mayn't I have been thumbtacking? mayn't you have been thumbtacking? mayn't he have been thumbtacking? mayn't we have been thumbtacking? mayn't you have been thumbtacking? mayn't they have been thumbtacking?