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