I could squint you could squint he could squint we could squint you could squint they could squint
V-ing form
I could be squinting you could be squinting he could be squinting we could be squinting you could be squinting they could be squinting
Perfect
I could have squinted you could have squinted he could have squinted we could have squinted you could have squinted they could have squinted
V-ing perfect
I could have been squinting you could have been squinting he could have been squinting we could have been squinting you could have been squinting they could have been squinting
Negation
Simple form
I could not squint you could not squint he could not squint we could not squint you could not squint they could not squint
V-ing form
I could not be squinting you could not be squinting he could not be squinting we could not be squinting you could not be squinting they could not be squinting
Perfect
I could not have squinted you could not have squinted he could not have squinted we could not have squinted you could not have squinted they could not have squinted
V-ing perfect
I could not have been squinting you could not have been squinting he could not have been squinting we could not have been squinting you could not have been squinting they could not have been squinting
Interrogative form
Simple form
could I squint? could you squint? could he squint? could we squint? could you squint? could they squint?
V-ing form
could I be squinting? could you be squinting? could he be squinting? could we be squinting? could you be squinting? could they be squinting?
Perfect
could I have squinted? could you have squinted? could he have squinted? could we have squinted? could you have squinted? could they have squinted?
V-ing perfect
could I have been squinting? could you have been squinting? could he have been squinting? could we have been squinting? could you have been squinting? could they have been squinting?
Interro-negative form
Simple form
could I not squint? could you not squint? could he not squint? could we not squint? could you not squint? could they not squint?
V-ing form
could I not be squinting? could you not be squinting? could he not be squinting? could we not be squinting? could you not be squinting? could they not be squinting?
Perfect
could I not have squinted? could you not have squinted? could he not have squinted? could we not have squinted? could you not have squinted? could they not have squinted?
V-ing perfect
could I not have been squinting? could you not have been squinting? could he not have been squinting? could we not have been squinting? could you not have been squinting? could they not have been squinting?