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