could specialize
Regular verb: specialize - specialized- specialized

Affirmation 	
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I could specialize
you could specialize
he could specialize
we could specialize
you could specialize
they could specialize 	I could be specializing
you could be specializing
he could be specializing
we could be specializing
you could be specializing
they could be specializing	I could have specialized
you could have specialized
he could have specialized
we could have specialized
you could have specialized
they could have specialized	I could have been specializing
you could have been specializing
he could have been specializing
we could have been specializing
you could have been specializing
they could have been specializing	

Negation 	
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I could not specialize
you could not specialize
he could not specialize
we could not specialize
you could not specialize
they could not specialize 	I could not be specializing
you could not be specializing
he could not be specializing
we could not be specializing
you could not be specializing
they could not be specializing	I could not have specialized
you could not have specialized
he could not have specialized
we could not have specialized
you could not have specialized
they could not have specialized	I could not have been specializing
you could not have been specializing
he could not have been specializing
we could not have been specializing
you could not have been specializing
they could not have been specializing	

Interrogative form 	
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could I specialize?
could you specialize?
could he specialize?
could we specialize?
could you specialize?
could they specialize? 	could I be specializing?
could you be specializing?
could he be specializing?
could we be specializing?
could you be specializing?
could they be specializing? 	could I have specialized?
could you have specialized?
could he have specialized?
could we have specialized?
could you have specialized?
could they have specialized? 	could I have been specializing?
could you have been specializing?
could he have been specializing?
could we have been specializing?
could you have been specializing?
could they have been specializing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not specialize?
could you not specialize?
could he not specialize?
could we not specialize?
could you not specialize?
could they not specialize? 	could I not be specializing?
could you not be specializing?
could he not be specializing?
could we not be specializing?
could you not be specializing?
could they not be specializing? 	could I not have specialized?
could you not have specialized?
could he not have specialized?
could we not have specialized?
could you not have specialized?
could they not have specialized? 	could I not have been specializing?
could you not have been specializing?
could he not have been specializing?
could we not have been specializing?
could you not have been specializing?
could they not have been specializing?