could invalid
Regular verb: invalid - invalided- invalided

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could invalid
you could invalid
he could invalid
we could invalid
you could invalid
they could invalid 	I could be invaliding
you could be invaliding
he could be invaliding
we could be invaliding
you could be invaliding
they could be invaliding	I could have invalided
you could have invalided
he could have invalided
we could have invalided
you could have invalided
they could have invalided	I could have been invaliding
you could have been invaliding
he could have been invaliding
we could have been invaliding
you could have been invaliding
they could have been invaliding	

Negation 	
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I could not invalid
you could not invalid
he could not invalid
we could not invalid
you could not invalid
they could not invalid 	I could not be invaliding
you could not be invaliding
he could not be invaliding
we could not be invaliding
you could not be invaliding
they could not be invaliding	I could not have invalided
you could not have invalided
he could not have invalided
we could not have invalided
you could not have invalided
they could not have invalided	I could not have been invaliding
you could not have been invaliding
he could not have been invaliding
we could not have been invaliding
you could not have been invaliding
they could not have been invaliding	

Interrogative form 	
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could I invalid?
could you invalid?
could he invalid?
could we invalid?
could you invalid?
could they invalid? 	could I be invaliding?
could you be invaliding?
could he be invaliding?
could we be invaliding?
could you be invaliding?
could they be invaliding? 	could I have invalided?
could you have invalided?
could he have invalided?
could we have invalided?
could you have invalided?
could they have invalided? 	could I have been invaliding?
could you have been invaliding?
could he have been invaliding?
could we have been invaliding?
could you have been invaliding?
could they have been invaliding? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not invalid?
could you not invalid?
could he not invalid?
could we not invalid?
could you not invalid?
could they not invalid? 	could I not be invaliding?
could you not be invaliding?
could he not be invaliding?
could we not be invaliding?
could you not be invaliding?
could they not be invaliding? 	could I not have invalided?
could you not have invalided?
could he not have invalided?
could we not have invalided?
could you not have invalided?
could they not have invalided? 	could I not have been invaliding?
could you not have been invaliding?
could he not have been invaliding?
could we not have been invaliding?
could you not have been invaliding?
could they not have been invaliding?