I could canvass you could canvass she could canvass we could canvass you could canvass they could canvass
V-ing form
I could be canvassing you could be canvassing she could be canvassing we could be canvassing you could be canvassing they could be canvassing
Perfect
I could have canvassed you could have canvassed she 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 she 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 she 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 she 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 she 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 she 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 she canvass? could we canvass? could you canvass? could they canvass?
V-ing form
could I be canvassing? could you be canvassing? could she be canvassing? could we be canvassing? could you be canvassing? could they be canvassing?
Perfect
could I have canvassed? could you have canvassed? could she 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 she 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 she 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 she 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 she 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 she have been canvassing? couldn't we have been canvassing? couldn't you have been canvassing? couldn't they have been canvassing?