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