I could mention you could mention he could mention we could mention you could mention they could mention
V-ing form
I could be mentioning you could be mentioning he could be mentioning we could be mentioning you could be mentioning they could be mentioning
Perfect
I could have mentioned you could have mentioned he could have mentioned we could have mentioned you could have mentioned they could have mentioned
V-ing perfect
I could have been mentioning you could have been mentioning he could have been mentioning we could have been mentioning you could have been mentioning they could have been mentioning
Negation
Simple form
I couldn't mention you couldn't mention he couldn't mention we couldn't mention you couldn't mention they couldn't mention
V-ing form
I couldn't be mentioning you couldn't be mentioning he couldn't be mentioning we couldn't be mentioning you couldn't be mentioning they couldn't be mentioning
Perfect
I couldn't have mentioned you couldn't have mentioned he couldn't have mentioned we couldn't have mentioned you couldn't have mentioned they couldn't have mentioned
V-ing perfect
I couldn't have been mentioning you couldn't have been mentioning he couldn't have been mentioning we couldn't have been mentioning you couldn't have been mentioning they couldn't have been mentioning
Interrogative form
Simple form
could I mention? could you mention? could he mention? could we mention? could you mention? could they mention?
V-ing form
could I be mentioning? could you be mentioning? could he be mentioning? could we be mentioning? could you be mentioning? could they be mentioning?
Perfect
could I have mentioned? could you have mentioned? could he have mentioned? could we have mentioned? could you have mentioned? could they have mentioned?
V-ing perfect
could I have been mentioning? could you have been mentioning? could he have been mentioning? could we have been mentioning? could you have been mentioning? could they have been mentioning?
Interro-negative form
Simple form
couldn't I mention? couldn't you mention? couldn't he mention? couldn't we mention? couldn't you mention? couldn't they mention?
V-ing form
couldn't I be mentioning? couldn't you be mentioning? couldn't he be mentioning? couldn't we be mentioning? couldn't you be mentioning? couldn't they be mentioning?
Perfect
couldn't I have mentioned? couldn't you have mentioned? couldn't he have mentioned? couldn't we have mentioned? couldn't you have mentioned? couldn't they have mentioned?
V-ing perfect
couldn't I have been mentioning? couldn't you have been mentioning? couldn't he have been mentioning? couldn't we have been mentioning? couldn't you have been mentioning? couldn't they have been mentioning?