could stratify
Verbo regular: stratify - stratified- stratified

Afirmación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I could stratify
you could stratify
he could stratify
we could stratify
you could stratify
they could stratify 	I could be stratifying
you could be stratifying
he could be stratifying
we could be stratifying
you could be stratifying
they could be stratifying	I could have stratified
you could have stratified
he could have stratified
we could have stratified
you could have stratified
they could have stratified	I could have been stratifying
you could have been stratifying
he could have been stratifying
we could have been stratifying
you could have been stratifying
they could have been stratifying	

Negación 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
I couldn't stratify
you couldn't stratify
he couldn't stratify
we couldn't stratify
you couldn't stratify
they couldn't stratify 	I couldn't be stratifying
you couldn't be stratifying
he couldn't be stratifying
we couldn't be stratifying
you couldn't be stratifying
they couldn't be stratifying	I couldn't have stratified
you couldn't have stratified
he couldn't have stratified
we couldn't have stratified
you couldn't have stratified
they couldn't have stratified	I couldn't have been stratifying
you couldn't have been stratifying
he couldn't have been stratifying
we couldn't have been stratifying
you couldn't have been stratifying
they couldn't have been stratifying	

Forma interrogativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
could I stratify?
could you stratify?
could he stratify?
could we stratify?
could you stratify?
could they stratify? 	could I be stratifying?
could you be stratifying?
could he be stratifying?
could we be stratifying?
could you be stratifying?
could they be stratifying? 	could I have stratified?
could you have stratified?
could he have stratified?
could we have stratified?
could you have stratified?
could they have stratified? 	could I have been stratifying?
could you have been stratifying?
could he have been stratifying?
could we have been stratifying?
could you have been stratifying?
could they have been stratifying? 	

Forma interro-negativa 	
Forma simple 	Forma con V-ing 	Perfecto 	Perfecto con V-ing 	
couldn't I stratify?
couldn't you stratify?
couldn't he stratify?
couldn't we stratify?
couldn't you stratify?
couldn't they stratify? 	couldn't I be stratifying?
couldn't you be stratifying?
couldn't he be stratifying?
couldn't we be stratifying?
couldn't you be stratifying?
couldn't they be stratifying? 	couldn't I have stratified?
couldn't you have stratified?
couldn't he have stratified?
couldn't we have stratified?
couldn't you have stratified?
couldn't they have stratified? 	couldn't I have been stratifying?
couldn't you have been stratifying?
couldn't he have been stratifying?
couldn't we have been stratifying?
couldn't you have been stratifying?
couldn't they have been stratifying?