I could skitter you could skitter she could skitter we could skitter you could skitter they could skitter
V-ing form
I could be skittering you could be skittering she could be skittering we could be skittering you could be skittering they could be skittering
Perfect
I could have skittered you could have skittered she could have skittered we could have skittered you could have skittered they could have skittered
V-ing perfect
I could have been skittering you could have been skittering she could have been skittering we could have been skittering you could have been skittering they could have been skittering
Negation
Simple form
I couldn't skitter you couldn't skitter she couldn't skitter we couldn't skitter you couldn't skitter they couldn't skitter
V-ing form
I couldn't be skittering you couldn't be skittering she couldn't be skittering we couldn't be skittering you couldn't be skittering they couldn't be skittering
Perfect
I couldn't have skittered you couldn't have skittered she couldn't have skittered we couldn't have skittered you couldn't have skittered they couldn't have skittered
V-ing perfect
I couldn't have been skittering you couldn't have been skittering she couldn't have been skittering we couldn't have been skittering you couldn't have been skittering they couldn't have been skittering
Interrogative form
Simple form
could I skitter? could you skitter? could she skitter? could we skitter? could you skitter? could they skitter?
V-ing form
could I be skittering? could you be skittering? could she be skittering? could we be skittering? could you be skittering? could they be skittering?
Perfect
could I have skittered? could you have skittered? could she have skittered? could we have skittered? could you have skittered? could they have skittered?
V-ing perfect
could I have been skittering? could you have been skittering? could she have been skittering? could we have been skittering? could you have been skittering? could they have been skittering?
Interro-negative form
Simple form
couldn't I skitter? couldn't you skitter? couldn't she skitter? couldn't we skitter? couldn't you skitter? couldn't they skitter?
V-ing form
couldn't I be skittering? couldn't you be skittering? couldn't she be skittering? couldn't we be skittering? couldn't you be skittering? couldn't they be skittering?
Perfect
couldn't I have skittered? couldn't you have skittered? couldn't she have skittered? couldn't we have skittered? couldn't you have skittered? couldn't they have skittered?
V-ing perfect
couldn't I have been skittering? couldn't you have been skittering? couldn't she have been skittering? couldn't we have been skittering? couldn't you have been skittering? couldn't they have been skittering?