English verb conjugation
COULD INTERVENE

Regular verb: intervene - intervened - intervened

Affirmation

Simple form	V-ing form
I could intervene you could intervene she could intervene we could intervene you could intervene they could intervene	I could be intervening you could be intervening she 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 she 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 she 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 she 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 she 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 she 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 she 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 she intervene? could we intervene? could you intervene? could they intervene?	could I be intervening? could you be intervening? could she 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 she 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 she 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 she 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 she 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 she 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 she have been intervening? couldn't we have been intervening? couldn't you have been intervening? couldn't they have been intervening?