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