I could flow you could flow she could flow we could flow you could flow they could flow
V-ing form
I could be flowing you could be flowing she could be flowing we could be flowing you could be flowing they could be flowing
Perfect
I could have flowed you could have flowed she could have flowed we could have flowed you could have flowed they could have flowed
V-ing perfect
I could have been flowing you could have been flowing she could have been flowing we could have been flowing you could have been flowing they could have been flowing
Negation
Simple form
I couldn't flow you couldn't flow she couldn't flow we couldn't flow you couldn't flow they couldn't flow
V-ing form
I couldn't be flowing you couldn't be flowing she couldn't be flowing we couldn't be flowing you couldn't be flowing they couldn't be flowing
Perfect
I couldn't have flowed you couldn't have flowed she couldn't have flowed we couldn't have flowed you couldn't have flowed they couldn't have flowed
V-ing perfect
I couldn't have been flowing you couldn't have been flowing she couldn't have been flowing we couldn't have been flowing you couldn't have been flowing they couldn't have been flowing
Interrogative form
Simple form
could I flow? could you flow? could she flow? could we flow? could you flow? could they flow?
V-ing form
could I be flowing? could you be flowing? could she be flowing? could we be flowing? could you be flowing? could they be flowing?
Perfect
could I have flowed? could you have flowed? could she have flowed? could we have flowed? could you have flowed? could they have flowed?
V-ing perfect
could I have been flowing? could you have been flowing? could she have been flowing? could we have been flowing? could you have been flowing? could they have been flowing?
Interro-negative form
Simple form
couldn't I flow? couldn't you flow? couldn't she flow? couldn't we flow? couldn't you flow? couldn't they flow?
V-ing form
couldn't I be flowing? couldn't you be flowing? couldn't she be flowing? couldn't we be flowing? couldn't you be flowing? couldn't they be flowing?
Perfect
couldn't I have flowed? couldn't you have flowed? couldn't she have flowed? couldn't we have flowed? couldn't you have flowed? couldn't they have flowed?
V-ing perfect
couldn't I have been flowing? couldn't you have been flowing? couldn't she have been flowing? couldn't we have been flowing? couldn't you have been flowing? couldn't they have been flowing?