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