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