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