can stack
Verbo regular: stack - stacked- stacked

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I can stack
you can stack
he can stack
we can stack
you can stack
they can stack 	I can be stacking
you can be stacking
he can be stacking
we can be stacking
you can be stacking
they can be stacking	I can have stacked
you can have stacked
he can have stacked
we can have stacked
you can have stacked
they can have stacked	I can have been stacking
you can have been stacking
he can have been stacking
we can have been stacking
you can have been stacking
they can have been stacking	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I can't stack
you can't stack
he can't stack
we can't stack
you can't stack
they can't stack 	I can't be stacking
you can't be stacking
he can't be stacking
we can't be stacking
you can't be stacking
they can't be stacking	I can't have stacked
you can't have stacked
he can't have stacked
we can't have stacked
you can't have stacked
they can't have stacked	I can't have been stacking
you can't have been stacking
he can't have been stacking
we can't have been stacking
you can't have been stacking
they can't have been stacking	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can I stack?
can you stack?
can he stack?
can we stack?
can you stack?
can they stack? 	can I be stacking?
can you be stacking?
can he be stacking?
can we be stacking?
can you be stacking?
can they be stacking? 	can I have stacked?
can you have stacked?
can he have stacked?
can we have stacked?
can you have stacked?
can they have stacked? 	can I have been stacking?
can you have been stacking?
can he have been stacking?
can we have been stacking?
can you have been stacking?
can they have been stacking? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
can't I stack?
can't you stack?
can't he stack?
can't we stack?
can't you stack?
can't they stack? 	can't I be stacking?
can't you be stacking?
can't he be stacking?
can't we be stacking?
can't you be stacking?
can't they be stacking? 	can't I have stacked?
can't you have stacked?
can't he have stacked?
can't we have stacked?
can't you have stacked?
can't they have stacked? 	can't I have been stacking?
can't you have been stacking?
can't he have been stacking?
can't we have been stacking?
can't you have been stacking?
can't they have been stacking?