I could forbid you could forbid he could forbid we could forbid you could forbid they could forbid
V-ing form
I could be forbidding you could be forbidding he could be forbidding we could be forbidding you could be forbidding they could be forbidding
Perfect
I could have forbid, forbidden you could have forbid, forbidden he could have forbid, forbidden we could have forbid, forbidden you could have forbid, forbidden they could have forbid, forbidden
V-ing perfect
I could have been forbidding you could have been forbidding he could have been forbidding we could have been forbidding you could have been forbidding they could have been forbidding
Negation
Simple form
I couldn't forbid you couldn't forbid he couldn't forbid we couldn't forbid you couldn't forbid they couldn't forbid
V-ing form
I couldn't be forbidding you couldn't be forbidding he couldn't be forbidding we couldn't be forbidding you couldn't be forbidding they couldn't be forbidding
Perfect
I couldn't have forbid, forbidden you couldn't have forbid, forbidden he couldn't have forbid, forbidden we couldn't have forbid, forbidden you couldn't have forbid, forbidden they couldn't have forbid, forbidden
V-ing perfect
I couldn't have been forbidding you couldn't have been forbidding he couldn't have been forbidding we couldn't have been forbidding you couldn't have been forbidding they couldn't have been forbidding
Interrogative form
Simple form
could I forbid? could you forbid? could he forbid? could we forbid? could you forbid? could they forbid?
V-ing form
could I be forbidding? could you be forbidding? could he be forbidding? could we be forbidding? could you be forbidding? could they be forbidding?
Perfect
could I have forbid, forbidden? could you have forbid, forbidden? could he have forbid, forbidden? could we have forbid, forbidden? could you have forbid, forbidden? could they have forbid, forbidden?
V-ing perfect
could I have been forbidding? could you have been forbidding? could he have been forbidding? could we have been forbidding? could you have been forbidding? could they have been forbidding?
Interro-negative form
Simple form
couldn't I forbid? couldn't you forbid? couldn't he forbid? couldn't we forbid? couldn't you forbid? couldn't they forbid?
V-ing form
couldn't I be forbidding? couldn't you be forbidding? couldn't he be forbidding? couldn't we be forbidding? couldn't you be forbidding? couldn't they be forbidding?
Perfect
couldn't I have forbid, forbidden? couldn't you have forbid, forbidden? couldn't he have forbid, forbidden? couldn't we have forbid, forbidden? couldn't you have forbid, forbidden? couldn't they have forbid, forbidden?
V-ing perfect
couldn't I have been forbidding? couldn't you have been forbidding? couldn't he have been forbidding? couldn't we have been forbidding? couldn't you have been forbidding? couldn't they have been forbidding?