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