could impair
Regular verb: impair - impaired- impaired

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could impair
you could impair
he could impair
we could impair
you could impair
they could impair 	I could be impairing
you could be impairing
he could be impairing
we could be impairing
you could be impairing
they could be impairing	I could have impaired
you could have impaired
he could have impaired
we could have impaired
you could have impaired
they could have impaired	I could have been impairing
you could have been impairing
he could have been impairing
we could have been impairing
you could have been impairing
they could have been impairing	

Negation 	
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I couldn't impair
you couldn't impair
he couldn't impair
we couldn't impair
you couldn't impair
they couldn't impair 	I couldn't be impairing
you couldn't be impairing
he couldn't be impairing
we couldn't be impairing
you couldn't be impairing
they couldn't be impairing	I couldn't have impaired
you couldn't have impaired
he couldn't have impaired
we couldn't have impaired
you couldn't have impaired
they couldn't have impaired	I couldn't have been impairing
you couldn't have been impairing
he couldn't have been impairing
we couldn't have been impairing
you couldn't have been impairing
they couldn't have been impairing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I impair?
could you impair?
could he impair?
could we impair?
could you impair?
could they impair? 	could I be impairing?
could you be impairing?
could he be impairing?
could we be impairing?
could you be impairing?
could they be impairing? 	could I have impaired?
could you have impaired?
could he have impaired?
could we have impaired?
could you have impaired?
could they have impaired? 	could I have been impairing?
could you have been impairing?
could he have been impairing?
could we have been impairing?
could you have been impairing?
could they have been impairing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I impair?
couldn't you impair?
couldn't he impair?
couldn't we impair?
couldn't you impair?
couldn't they impair? 	couldn't I be impairing?
couldn't you be impairing?
couldn't he be impairing?
couldn't we be impairing?
couldn't you be impairing?
couldn't they be impairing? 	couldn't I have impaired?
couldn't you have impaired?
couldn't he have impaired?
couldn't we have impaired?
couldn't you have impaired?
couldn't they have impaired? 	couldn't I have been impairing?
couldn't you have been impairing?
couldn't he have been impairing?
couldn't we have been impairing?
couldn't you have been impairing?
couldn't they have been impairing?