could invalid
Regular verb: invalid - invalided- invalided

Affirmation 	
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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 couldn't invalid
you couldn't invalid
he couldn't invalid
we couldn't invalid
you couldn't invalid
they couldn't invalid 	I couldn't be invaliding
you couldn't be invaliding
he couldn't be invaliding
we couldn't be invaliding
you couldn't be invaliding
they couldn't be invaliding	I couldn't have invalided
you couldn't have invalided
he couldn't have invalided
we couldn't have invalided
you couldn't have invalided
they couldn't have invalided	I couldn't have been invaliding
you couldn't have been invaliding
he couldn't have been invaliding
we couldn't have been invaliding
you couldn't have been invaliding
they couldn't 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 	
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couldn't I invalid?
couldn't you invalid?
couldn't he invalid?
couldn't we invalid?
couldn't you invalid?
couldn't they invalid? 	couldn't I be invaliding?
couldn't you be invaliding?
couldn't he be invaliding?
couldn't we be invaliding?
couldn't you be invaliding?
couldn't they be invaliding? 	couldn't I have invalided?
couldn't you have invalided?
couldn't he have invalided?
couldn't we have invalided?
couldn't you have invalided?
couldn't they have invalided? 	couldn't I have been invaliding?
couldn't you have been invaliding?
couldn't he have been invaliding?
couldn't we have been invaliding?
couldn't you have been invaliding?
couldn't they have been invaliding?