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