could crystallize
Regular verb: crystallize - crystallized- crystallized

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could crystallize
you could crystallize
she could crystallize
we could crystallize
you could crystallize
they could crystallize 	I could be crystallizing
you could be crystallizing
she could be crystallizing
we could be crystallizing
you could be crystallizing
they could be crystallizing	I could have crystallized
you could have crystallized
she could have crystallized
we could have crystallized
you could have crystallized
they could have crystallized	I could have been crystallizing
you could have been crystallizing
she could have been crystallizing
we could have been crystallizing
you could have been crystallizing
they could have been crystallizing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't crystallize
you couldn't crystallize
she couldn't crystallize
we couldn't crystallize
you couldn't crystallize
they couldn't crystallize 	I couldn't be crystallizing
you couldn't be crystallizing
she couldn't be crystallizing
we couldn't be crystallizing
you couldn't be crystallizing
they couldn't be crystallizing	I couldn't have crystallized
you couldn't have crystallized
she couldn't have crystallized
we couldn't have crystallized
you couldn't have crystallized
they couldn't have crystallized	I couldn't have been crystallizing
you couldn't have been crystallizing
she couldn't have been crystallizing
we couldn't have been crystallizing
you couldn't have been crystallizing
they couldn't have been crystallizing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I crystallize?
could you crystallize?
could she crystallize?
could we crystallize?
could you crystallize?
could they crystallize? 	could I be crystallizing?
could you be crystallizing?
could she be crystallizing?
could we be crystallizing?
could you be crystallizing?
could they be crystallizing? 	could I have crystallized?
could you have crystallized?
could she have crystallized?
could we have crystallized?
could you have crystallized?
could they have crystallized? 	could I have been crystallizing?
could you have been crystallizing?
could she have been crystallizing?
could we have been crystallizing?
could you have been crystallizing?
could they have been crystallizing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I crystallize?
couldn't you crystallize?
couldn't she crystallize?
couldn't we crystallize?
couldn't you crystallize?
couldn't they crystallize? 	couldn't I be crystallizing?
couldn't you be crystallizing?
couldn't she be crystallizing?
couldn't we be crystallizing?
couldn't you be crystallizing?
couldn't they be crystallizing? 	couldn't I have crystallized?
couldn't you have crystallized?
couldn't she have crystallized?
couldn't we have crystallized?
couldn't you have crystallized?
couldn't they have crystallized? 	couldn't I have been crystallizing?
couldn't you have been crystallizing?
couldn't she have been crystallizing?
couldn't we have been crystallizing?
couldn't you have been crystallizing?
couldn't they have been crystallizing?