could purify
Regular verb: purify - purified- purified

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could purify
you could purify
she could purify
we could purify
you could purify
they could purify 	I could be purifying
you could be purifying
she could be purifying
we could be purifying
you could be purifying
they could be purifying	I could have purified
you could have purified
she could have purified
we could have purified
you could have purified
they could have purified	I could have been purifying
you could have been purifying
she could have been purifying
we could have been purifying
you could have been purifying
they could have been purifying	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't purify
you couldn't purify
she couldn't purify
we couldn't purify
you couldn't purify
they couldn't purify 	I couldn't be purifying
you couldn't be purifying
she couldn't be purifying
we couldn't be purifying
you couldn't be purifying
they couldn't be purifying	I couldn't have purified
you couldn't have purified
she couldn't have purified
we couldn't have purified
you couldn't have purified
they couldn't have purified	I couldn't have been purifying
you couldn't have been purifying
she couldn't have been purifying
we couldn't have been purifying
you couldn't have been purifying
they couldn't have been purifying	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I purify?
could you purify?
could she purify?
could we purify?
could you purify?
could they purify? 	could I be purifying?
could you be purifying?
could she be purifying?
could we be purifying?
could you be purifying?
could they be purifying? 	could I have purified?
could you have purified?
could she have purified?
could we have purified?
could you have purified?
could they have purified? 	could I have been purifying?
could you have been purifying?
could she have been purifying?
could we have been purifying?
could you have been purifying?
could they have been purifying? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I purify?
couldn't you purify?
couldn't she purify?
couldn't we purify?
couldn't you purify?
couldn't they purify? 	couldn't I be purifying?
couldn't you be purifying?
couldn't she be purifying?
couldn't we be purifying?
couldn't you be purifying?
couldn't they be purifying? 	couldn't I have purified?
couldn't you have purified?
couldn't she have purified?
couldn't we have purified?
couldn't you have purified?
couldn't they have purified? 	couldn't I have been purifying?
couldn't you have been purifying?
couldn't she have been purifying?
couldn't we have been purifying?
couldn't you have been purifying?
couldn't they have been purifying?