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