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