could differentiate
Regular verb: differentiate - differentiated- differentiated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could differentiate
you could differentiate
she could differentiate
we could differentiate
you could differentiate
they could differentiate 	I could be differentiating
you could be differentiating
she could be differentiating
we could be differentiating
you could be differentiating
they could be differentiating	I could have differentiated
you could have differentiated
she could have differentiated
we could have differentiated
you could have differentiated
they could have differentiated	I could have been differentiating
you could have been differentiating
she could have been differentiating
we could have been differentiating
you could have been differentiating
they could have been differentiating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't differentiate
you couldn't differentiate
she couldn't differentiate
we couldn't differentiate
you couldn't differentiate
they couldn't differentiate 	I couldn't be differentiating
you couldn't be differentiating
she couldn't be differentiating
we couldn't be differentiating
you couldn't be differentiating
they couldn't be differentiating	I couldn't have differentiated
you couldn't have differentiated
she couldn't have differentiated
we couldn't have differentiated
you couldn't have differentiated
they couldn't have differentiated	I couldn't have been differentiating
you couldn't have been differentiating
she couldn't have been differentiating
we couldn't have been differentiating
you couldn't have been differentiating
they couldn't have been differentiating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I differentiate?
could you differentiate?
could she differentiate?
could we differentiate?
could you differentiate?
could they differentiate? 	could I be differentiating?
could you be differentiating?
could she be differentiating?
could we be differentiating?
could you be differentiating?
could they be differentiating? 	could I have differentiated?
could you have differentiated?
could she have differentiated?
could we have differentiated?
could you have differentiated?
could they have differentiated? 	could I have been differentiating?
could you have been differentiating?
could she have been differentiating?
could we have been differentiating?
could you have been differentiating?
could they have been differentiating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I differentiate?
couldn't you differentiate?
couldn't she differentiate?
couldn't we differentiate?
couldn't you differentiate?
couldn't they differentiate? 	couldn't I be differentiating?
couldn't you be differentiating?
couldn't she be differentiating?
couldn't we be differentiating?
couldn't you be differentiating?
couldn't they be differentiating? 	couldn't I have differentiated?
couldn't you have differentiated?
couldn't she have differentiated?
couldn't we have differentiated?
couldn't you have differentiated?
couldn't they have differentiated? 	couldn't I have been differentiating?
couldn't you have been differentiating?
couldn't she have been differentiating?
couldn't we have been differentiating?
couldn't you have been differentiating?
couldn't they have been differentiating?