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