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