should stack
Regular verb: stack - stacked- stacked

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

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

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

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