can certify
Regular verb: certify - certified- certified

Affirmation 	
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I can certify
you can certify
she can certify
we can certify
you can certify
they can certify 	I can be certifying
you can be certifying
she can be certifying
we can be certifying
you can be certifying
they can be certifying	I can have certified
you can have certified
she can have certified
we can have certified
you can have certified
they can have certified	I can have been certifying
you can have been certifying
she can have been certifying
we can have been certifying
you can have been certifying
they can have been certifying	

Negation 	
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I can't certify
you can't certify
she can't certify
we can't certify
you can't certify
they can't certify 	I can't be certifying
you can't be certifying
she can't be certifying
we can't be certifying
you can't be certifying
they can't be certifying	I can't have certified
you can't have certified
she can't have certified
we can't have certified
you can't have certified
they can't have certified	I can't have been certifying
you can't have been certifying
she can't have been certifying
we can't have been certifying
you can't have been certifying
they can't have been certifying	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I certify?
can you certify?
can she certify?
can we certify?
can you certify?
can they certify? 	can I be certifying?
can you be certifying?
can she be certifying?
can we be certifying?
can you be certifying?
can they be certifying? 	can I have certified?
can you have certified?
can she have certified?
can we have certified?
can you have certified?
can they have certified? 	can I have been certifying?
can you have been certifying?
can she have been certifying?
can we have been certifying?
can you have been certifying?
can they have been certifying? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I certify?
can't you certify?
can't she certify?
can't we certify?
can't you certify?
can't they certify? 	can't I be certifying?
can't you be certifying?
can't she be certifying?
can't we be certifying?
can't you be certifying?
can't they be certifying? 	can't I have certified?
can't you have certified?
can't she have certified?
can't we have certified?
can't you have certified?
can't they have certified? 	can't I have been certifying?
can't you have been certifying?
can't she have been certifying?
can't we have been certifying?
can't you have been certifying?
can't they have been certifying?