could destabilise
Regular verb: destabilise - destabilised- destabilised

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could destabilise
you could destabilise
he could destabilise
we could destabilise
you could destabilise
they could destabilise 	I could be destabilising
you could be destabilising
he could be destabilising
we could be destabilising
you could be destabilising
they could be destabilising	I could have destabilised
you could have destabilised
he could have destabilised
we could have destabilised
you could have destabilised
they could have destabilised	I could have been destabilising
you could have been destabilising
he could have been destabilising
we could have been destabilising
you could have been destabilising
they could have been destabilising	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't destabilise
you couldn't destabilise
he couldn't destabilise
we couldn't destabilise
you couldn't destabilise
they couldn't destabilise 	I couldn't be destabilising
you couldn't be destabilising
he couldn't be destabilising
we couldn't be destabilising
you couldn't be destabilising
they couldn't be destabilising	I couldn't have destabilised
you couldn't have destabilised
he couldn't have destabilised
we couldn't have destabilised
you couldn't have destabilised
they couldn't have destabilised	I couldn't have been destabilising
you couldn't have been destabilising
he couldn't have been destabilising
we couldn't have been destabilising
you couldn't have been destabilising
they couldn't have been destabilising	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I destabilise?
could you destabilise?
could he destabilise?
could we destabilise?
could you destabilise?
could they destabilise? 	could I be destabilising?
could you be destabilising?
could he be destabilising?
could we be destabilising?
could you be destabilising?
could they be destabilising? 	could I have destabilised?
could you have destabilised?
could he have destabilised?
could we have destabilised?
could you have destabilised?
could they have destabilised? 	could I have been destabilising?
could you have been destabilising?
could he have been destabilising?
could we have been destabilising?
could you have been destabilising?
could they have been destabilising? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I destabilise?
couldn't you destabilise?
couldn't he destabilise?
couldn't we destabilise?
couldn't you destabilise?
couldn't they destabilise? 	couldn't I be destabilising?
couldn't you be destabilising?
couldn't he be destabilising?
couldn't we be destabilising?
couldn't you be destabilising?
couldn't they be destabilising? 	couldn't I have destabilised?
couldn't you have destabilised?
couldn't he have destabilised?
couldn't we have destabilised?
couldn't you have destabilised?
couldn't they have destabilised? 	couldn't I have been destabilising?
couldn't you have been destabilising?
couldn't he have been destabilising?
couldn't we have been destabilising?
couldn't you have been destabilising?
couldn't they have been destabilising?