English verb conjugation
COULD REVISE

Regular verb: revise - revised - revised

Affirmation

Simple form	V-ing form
I could revise you could revise he could revise we could revise you could revise they could revise	I could be revising you could be revising he could be revising we could be revising you could be revising they could be revising
Perfect	V-ing perfect
I could have revised you could have revised he could have revised we could have revised you could have revised they could have revised	I could have been revising you could have been revising he could have been revising we could have been revising you could have been revising they could have been revising

Negation

Simple form	V-ing form
I couldn't revise you couldn't revise he couldn't revise we couldn't revise you couldn't revise they couldn't revise	I couldn't be revising you couldn't be revising he couldn't be revising we couldn't be revising you couldn't be revising they couldn't be revising
Perfect	V-ing perfect
I couldn't have revised you couldn't have revised he couldn't have revised we couldn't have revised you couldn't have revised they couldn't have revised	I couldn't have been revising you couldn't have been revising he couldn't have been revising we couldn't have been revising you couldn't have been revising they couldn't have been revising

Interrogative form

Simple form	V-ing form
could I revise? could you revise? could he revise? could we revise? could you revise? could they revise?	could I be revising? could you be revising? could he be revising? could we be revising? could you be revising? could they be revising?
Perfect	V-ing perfect
could I have revised? could you have revised? could he have revised? could we have revised? could you have revised? could they have revised?	could I have been revising? could you have been revising? could he have been revising? could we have been revising? could you have been revising? could they have been revising?

Interro-negative form

Simple form	V-ing form
couldn't I revise? couldn't you revise? couldn't he revise? couldn't we revise? couldn't you revise? couldn't they revise?	couldn't I be revising? couldn't you be revising? couldn't he be revising? couldn't we be revising? couldn't you be revising? couldn't they be revising?
Perfect	V-ing perfect
couldn't I have revised? couldn't you have revised? couldn't he have revised? couldn't we have revised? couldn't you have revised? couldn't they have revised?	couldn't I have been revising? couldn't you have been revising? couldn't he have been revising? couldn't we have been revising? couldn't you have been revising? couldn't they have been revising?