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