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