could diminish
Regular verb: diminish - diminished- diminished

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could diminish
you could diminish
he could diminish
we could diminish
you could diminish
they could diminish 	I could be diminishing
you could be diminishing
he could be diminishing
we could be diminishing
you could be diminishing
they could be diminishing	I could have diminished
you could have diminished
he could have diminished
we could have diminished
you could have diminished
they could have diminished	I could have been diminishing
you could have been diminishing
he could have been diminishing
we could have been diminishing
you could have been diminishing
they could have been diminishing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't diminish
you couldn't diminish
he couldn't diminish
we couldn't diminish
you couldn't diminish
they couldn't diminish 	I couldn't be diminishing
you couldn't be diminishing
he couldn't be diminishing
we couldn't be diminishing
you couldn't be diminishing
they couldn't be diminishing	I couldn't have diminished
you couldn't have diminished
he couldn't have diminished
we couldn't have diminished
you couldn't have diminished
they couldn't have diminished	I couldn't have been diminishing
you couldn't have been diminishing
he couldn't have been diminishing
we couldn't have been diminishing
you couldn't have been diminishing
they couldn't have been diminishing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I diminish?
could you diminish?
could he diminish?
could we diminish?
could you diminish?
could they diminish? 	could I be diminishing?
could you be diminishing?
could he be diminishing?
could we be diminishing?
could you be diminishing?
could they be diminishing? 	could I have diminished?
could you have diminished?
could he have diminished?
could we have diminished?
could you have diminished?
could they have diminished? 	could I have been diminishing?
could you have been diminishing?
could he have been diminishing?
could we have been diminishing?
could you have been diminishing?
could they have been diminishing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I diminish?
couldn't you diminish?
couldn't he diminish?
couldn't we diminish?
couldn't you diminish?
couldn't they diminish? 	couldn't I be diminishing?
couldn't you be diminishing?
couldn't he be diminishing?
couldn't we be diminishing?
couldn't you be diminishing?
couldn't they be diminishing? 	couldn't I have diminished?
couldn't you have diminished?
couldn't he have diminished?
couldn't we have diminished?
couldn't you have diminished?
couldn't they have diminished? 	couldn't I have been diminishing?
couldn't you have been diminishing?
couldn't he have been diminishing?
couldn't we have been diminishing?
couldn't you have been diminishing?
couldn't they have been diminishing?