English verb conjugation
COULD INTERVENE

Regular verb: intervene - intervened - intervened

Affirmation

Simple form	V-ing form
I could intervene you could intervene he could intervene we could intervene you could intervene they could intervene	I could be intervening you could be intervening he could be intervening we could be intervening you could be intervening they could be intervening
Perfect	V-ing perfect
I could have intervened you could have intervened he could have intervened we could have intervened you could have intervened they could have intervened	I could have been intervening you could have been intervening he could have been intervening we could have been intervening you could have been intervening they could have been intervening

Negation

Simple form	V-ing form
I couldn't intervene you couldn't intervene he couldn't intervene we couldn't intervene you couldn't intervene they couldn't intervene	I couldn't be intervening you couldn't be intervening he couldn't be intervening we couldn't be intervening you couldn't be intervening they couldn't be intervening
Perfect	V-ing perfect
I couldn't have intervened you couldn't have intervened he couldn't have intervened we couldn't have intervened you couldn't have intervened they couldn't have intervened	I couldn't have been intervening you couldn't have been intervening he couldn't have been intervening we couldn't have been intervening you couldn't have been intervening they couldn't have been intervening

Interrogative form

Simple form	V-ing form
could I intervene? could you intervene? could he intervene? could we intervene? could you intervene? could they intervene?	could I be intervening? could you be intervening? could he be intervening? could we be intervening? could you be intervening? could they be intervening?
Perfect	V-ing perfect
could I have intervened? could you have intervened? could he have intervened? could we have intervened? could you have intervened? could they have intervened?	could I have been intervening? could you have been intervening? could he have been intervening? could we have been intervening? could you have been intervening? could they have been intervening?

Interro-negative form

Simple form	V-ing form
couldn't I intervene? couldn't you intervene? couldn't he intervene? couldn't we intervene? couldn't you intervene? couldn't they intervene?	couldn't I be intervening? couldn't you be intervening? couldn't he be intervening? couldn't we be intervening? couldn't you be intervening? couldn't they be intervening?
Perfect	V-ing perfect
couldn't I have intervened? couldn't you have intervened? couldn't he have intervened? couldn't we have intervened? couldn't you have intervened? couldn't they have intervened?	couldn't I have been intervening? couldn't you have been intervening? couldn't he have been intervening? couldn't we have been intervening? couldn't you have been intervening? couldn't they have been intervening?