English verb conjugation
MAY STACK

Regular verb: stack - stacked - stacked

Affirmation

Simple form	V-ing form
I may stack you may stack he may stack we may stack you may stack they may stack	I may be stacking you may be stacking he may be stacking we may be stacking you may be stacking they may be stacking
Perfect	V-ing perfect
I may have stacked you may have stacked he may have stacked we may have stacked you may have stacked they may have stacked	I may have been stacking you may have been stacking he may have been stacking we may have been stacking you may have been stacking they may have been stacking

Negation

Simple form	V-ing form
I may not stack you may not stack he may not stack we may not stack you may not stack they may not stack	I may not be stacking you may not be stacking he may not be stacking we may not be stacking you may not be stacking they may not be stacking
Perfect	V-ing perfect
I may not have stacked you may not have stacked he may not have stacked we may not have stacked you may not have stacked they may not have stacked	I may not have been stacking you may not have been stacking he may not have been stacking we may not have been stacking you may not have been stacking they may not have been stacking

Interrogative form

Simple form	V-ing form
may I stack? may you stack? may he stack? may we stack? may you stack? may they stack?	may I be stacking? may you be stacking? may he be stacking? may we be stacking? may you be stacking? may they be stacking?
Perfect	V-ing perfect
may I have stacked? may you have stacked? may he have stacked? may we have stacked? may you have stacked? may they have stacked?	may I have been stacking? may you have been stacking? may he have been stacking? may we have been stacking? may you have been stacking? may they have been stacking?

Interro-negative form

Simple form	V-ing form
may I not stack? may you not stack? may he not stack? may we not stack? may you not stack? may they not stack?	may I not be stacking? may you not be stacking? may he not be stacking? may we not be stacking? may you not be stacking? may they not be stacking?
Perfect	V-ing perfect
may I not have stacked? may you not have stacked? may he not have stacked? may we not have stacked? may you not have stacked? may they not have stacked?	may I not have been stacking? may you not have been stacking? may he not have been stacking? may we not have been stacking? may you not have been stacking? may they not have been stacking?