English verb conjugation
COULD CHANGE

Regular verb: change - changed - changed

Affirmation

Simple form	V-ing form
I could change you could change he could change we could change you could change they could change	I could be changing you could be changing he could be changing we could be changing you could be changing they could be changing
Perfect	V-ing perfect
I could have changed you could have changed he could have changed we could have changed you could have changed they could have changed	I could have been changing you could have been changing he could have been changing we could have been changing you could have been changing they could have been changing

Negation

Simple form	V-ing form
I couldn't change you couldn't change he couldn't change we couldn't change you couldn't change they couldn't change	I couldn't be changing you couldn't be changing he couldn't be changing we couldn't be changing you couldn't be changing they couldn't be changing
Perfect	V-ing perfect
I couldn't have changed you couldn't have changed he couldn't have changed we couldn't have changed you couldn't have changed they couldn't have changed	I couldn't have been changing you couldn't have been changing he couldn't have been changing we couldn't have been changing you couldn't have been changing they couldn't have been changing

Interrogative form

Simple form	V-ing form
could I change? could you change? could he change? could we change? could you change? could they change?	could I be changing? could you be changing? could he be changing? could we be changing? could you be changing? could they be changing?
Perfect	V-ing perfect
could I have changed? could you have changed? could he have changed? could we have changed? could you have changed? could they have changed?	could I have been changing? could you have been changing? could he have been changing? could we have been changing? could you have been changing? could they have been changing?

Interro-negative form

Simple form	V-ing form
couldn't I change? couldn't you change? couldn't he change? couldn't we change? couldn't you change? couldn't they change?	couldn't I be changing? couldn't you be changing? couldn't he be changing? couldn't we be changing? couldn't you be changing? couldn't they be changing?
Perfect	V-ing perfect
couldn't I have changed? couldn't you have changed? couldn't he have changed? couldn't we have changed? couldn't you have changed? couldn't they have changed?	couldn't I have been changing? couldn't you have been changing? couldn't he have been changing? couldn't we have been changing? couldn't you have been changing? couldn't they have been changing?