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