could invade
Regular verb: invade - invaded- invaded

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could invade
you could invade
he could invade
we could invade
you could invade
they could invade 	I could be invading
you could be invading
he could be invading
we could be invading
you could be invading
they could be invading	I could have invaded
you could have invaded
he could have invaded
we could have invaded
you could have invaded
they could have invaded	I could have been invading
you could have been invading
he could have been invading
we could have been invading
you could have been invading
they could have been invading	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't invade
you couldn't invade
he couldn't invade
we couldn't invade
you couldn't invade
they couldn't invade 	I couldn't be invading
you couldn't be invading
he couldn't be invading
we couldn't be invading
you couldn't be invading
they couldn't be invading	I couldn't have invaded
you couldn't have invaded
he couldn't have invaded
we couldn't have invaded
you couldn't have invaded
they couldn't have invaded	I couldn't have been invading
you couldn't have been invading
he couldn't have been invading
we couldn't have been invading
you couldn't have been invading
they couldn't have been invading	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I invade?
could you invade?
could he invade?
could we invade?
could you invade?
could they invade? 	could I be invading?
could you be invading?
could he be invading?
could we be invading?
could you be invading?
could they be invading? 	could I have invaded?
could you have invaded?
could he have invaded?
could we have invaded?
could you have invaded?
could they have invaded? 	could I have been invading?
could you have been invading?
could he have been invading?
could we have been invading?
could you have been invading?
could they have been invading? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I invade?
couldn't you invade?
couldn't he invade?
couldn't we invade?
couldn't you invade?
couldn't they invade? 	couldn't I be invading?
couldn't you be invading?
couldn't he be invading?
couldn't we be invading?
couldn't you be invading?
couldn't they be invading? 	couldn't I have invaded?
couldn't you have invaded?
couldn't he have invaded?
couldn't we have invaded?
couldn't you have invaded?
couldn't they have invaded? 	couldn't I have been invading?
couldn't you have been invading?
couldn't he have been invading?
couldn't we have been invading?
couldn't you have been invading?
couldn't they have been invading?