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