could certify
Regular verb: certify - certified- certified

Affirmation 	
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I could certify
you could certify
he could certify
we could certify
you could certify
they could certify 	I could be certifying
you could be certifying
he could be certifying
we could be certifying
you could be certifying
they could be certifying	I could have certified
you could have certified
he could have certified
we could have certified
you could have certified
they could have certified	I could have been certifying
you could have been certifying
he could have been certifying
we could have been certifying
you could have been certifying
they could have been certifying	

Negation 	
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I couldn't certify
you couldn't certify
he couldn't certify
we couldn't certify
you couldn't certify
they couldn't certify 	I couldn't be certifying
you couldn't be certifying
he couldn't be certifying
we couldn't be certifying
you couldn't be certifying
they couldn't be certifying	I couldn't have certified
you couldn't have certified
he couldn't have certified
we couldn't have certified
you couldn't have certified
they couldn't have certified	I couldn't have been certifying
you couldn't have been certifying
he couldn't have been certifying
we couldn't have been certifying
you couldn't have been certifying
they couldn't have been certifying	

Interrogative form 	
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could I certify?
could you certify?
could he certify?
could we certify?
could you certify?
could they certify? 	could I be certifying?
could you be certifying?
could he be certifying?
could we be certifying?
could you be certifying?
could they be certifying? 	could I have certified?
could you have certified?
could he have certified?
could we have certified?
could you have certified?
could they have certified? 	could I have been certifying?
could you have been certifying?
could he have been certifying?
could we have been certifying?
could you have been certifying?
could they have been certifying? 	

Interro-negative form 	
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couldn't I certify?
couldn't you certify?
couldn't he certify?
couldn't we certify?
couldn't you certify?
couldn't they certify? 	couldn't I be certifying?
couldn't you be certifying?
couldn't he be certifying?
couldn't we be certifying?
couldn't you be certifying?
couldn't they be certifying? 	couldn't I have certified?
couldn't you have certified?
couldn't he have certified?
couldn't we have certified?
couldn't you have certified?
couldn't they have certified? 	couldn't I have been certifying?
couldn't you have been certifying?
couldn't he have been certifying?
couldn't we have been certifying?
couldn't you have been certifying?
couldn't they have been certifying?