could decease
Regular verb: decease - deceased- deceased

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could decease
you could decease
he could decease
we could decease
you could decease
they could decease 	I could be deceasing
you could be deceasing
he could be deceasing
we could be deceasing
you could be deceasing
they could be deceasing	I could have deceased
you could have deceased
he could have deceased
we could have deceased
you could have deceased
they could have deceased	I could have been deceasing
you could have been deceasing
he could have been deceasing
we could have been deceasing
you could have been deceasing
they could have been deceasing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't decease
you couldn't decease
he couldn't decease
we couldn't decease
you couldn't decease
they couldn't decease 	I couldn't be deceasing
you couldn't be deceasing
he couldn't be deceasing
we couldn't be deceasing
you couldn't be deceasing
they couldn't be deceasing	I couldn't have deceased
you couldn't have deceased
he couldn't have deceased
we couldn't have deceased
you couldn't have deceased
they couldn't have deceased	I couldn't have been deceasing
you couldn't have been deceasing
he couldn't have been deceasing
we couldn't have been deceasing
you couldn't have been deceasing
they couldn't have been deceasing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I decease?
could you decease?
could he decease?
could we decease?
could you decease?
could they decease? 	could I be deceasing?
could you be deceasing?
could he be deceasing?
could we be deceasing?
could you be deceasing?
could they be deceasing? 	could I have deceased?
could you have deceased?
could he have deceased?
could we have deceased?
could you have deceased?
could they have deceased? 	could I have been deceasing?
could you have been deceasing?
could he have been deceasing?
could we have been deceasing?
could you have been deceasing?
could they have been deceasing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I decease?
couldn't you decease?
couldn't he decease?
couldn't we decease?
couldn't you decease?
couldn't they decease? 	couldn't I be deceasing?
couldn't you be deceasing?
couldn't he be deceasing?
couldn't we be deceasing?
couldn't you be deceasing?
couldn't they be deceasing? 	couldn't I have deceased?
couldn't you have deceased?
couldn't he have deceased?
couldn't we have deceased?
couldn't you have deceased?
couldn't they have deceased? 	couldn't I have been deceasing?
couldn't you have been deceasing?
couldn't he have been deceasing?
couldn't we have been deceasing?
couldn't you have been deceasing?
couldn't they have been deceasing?